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Purpose: To investigate the potential role of keratometry on whole globes in situ of deceased patients by assessing its repeatability and comparing it with sterile donor tomography after excision and preservation in organ culture., Methods: A sequence of 5 measurements was taken from 40 eyes in situ of deceased patients < 24 h after death using the portable Retinomax K-plus 3 (Bon, Tokyo, Japan). Keratometry of whole globes in situ, from which sclerocorneal discs were taken for organ culture, was compared to those obtained after measuring these sclerocorneal disks through their cell culture flask in medium I after 5 ± 4 days using the anterior segment optical coherence tomograph Casia 2 (Tomey Corp., Nagoya, Japan), and to 964 different donor corneas in medium II., Results: Cronbach's alpha of the in situ keratometry was 0.891 and 0.942 for the steepest and flattest corneal power (P). The steepest (44.5D) and flattest (41.1D) P as well as the astigmatism (3.4D) of in situ corneas remained unchanged after preserving sclerocorneal discs in medium I (respectively 44.7D [p = 0.09]; 41.4D [p = 0.17]; 3.3D [p = 0.09]). The comparison of the in situ values with the 964 measured different donor corneas in medium II showed significantly (p < 0.001) higher P at the steep (45.4D) and flat (43.9D) meridian and smaller astigmatism (1.4D) for sterile donor tomography., Conclusions: Measuring deceased patients' eyes in situ with the portable Retinomax K-plus 3 represents a feasible and reliably repeatable screening method in the eye bank. In comparison to donor tomography in medium I, it measures a similar power and astigmatism., (© 2023. The Author(s).)

Background: A new keratometric routine that employs power vector management for manual keratometers is described. This study evaluates the agreement of the new proposed keratometric technique with the classical one., Research Design and Methods: The applicability of a new keratometric routine was verified using Helmholtz's and Javal's keratometers. Results were obtained by two different and well-trained examiners over two different samples, one including 65 and the other 74 eyes, respectively. Both conventional keratometry and the newly proposed routine (named vecto-keratometry) were used in each eye to obtain the results. The clinical agreement between the methods was evaluated using Bland-Altman and Passing-Bablok analysis., Results: For Helmholtz's keratometer, Bland-Altman plots showed good agreement between methods for both astigmatic components being J 0  = 0.04 ± 0.20 D and J 45  = -0.07 ± 0.17 D. For Javal's keratometer, Passing-Bablok regression test determined regression line for J 0 difference as y 0  = 1.03, confidence interval: [0.98, 1.10] and regression line for J 45 difference as y 45  = 0.97, confidence interval: [0.83, 1.12]., Conclusions: Vecto-keratometry provides accurate clinical results. It has been demonstrated that there are no significant differences between methods in any of the power vector astigmatic components; thus, both methods can be applied interchangeably.

Objectives: The purpose was to study the association between ocular dominance, refractive status, and biometric parameters., Methods: Ocular dominance was assessed on consenting participants with non-pathological eyes using "hole-in-the-card test." The participants were then examined for visual acuity, biometric measurements, and refraction. Data were analyzed using IBM SPSS software., Results: Among a total of 660 participants in our study, right eye dominance was found in 508 (76.97%) participants. We found that horizontal keratometry readings (K1) were greater in the dominant eye compared to the non-dominant eye, showing a statistically significant difference in emmetropes (p<0.001) and hyperopes (p<0.001). The axial length was found to be longer but not significantly greater in dominant eye among while it was significant among myopes (p<0.001) and hyperopes (p<0.001). In myopic anisometropes, the axial length was significantly longer and more myopic in the dominant eye (24.0±0.7 mm) than non-dominant eye (23.9±0.4 mm) while the non-dominant eye was more hyperopic in anisometropic hyperopes., Conclusion: Right eye was dominant in majority of participants. The dominant eye was more myopic and had greater axial length in anisometropes. The dominant eye was more astigmatic than the non-dominant eye. Visual acuity was not affected by ocular dominance. The mean difference in biometric measurements was significantly greater in hyperopic eyes. The assessment of ocular dominance could improve patient satisfaction in refractive surgeries and monovision treatments. Treatment protocols could be fine-tuned based on ocular dominance. Normative data in various biometric measurements could take into consideration laterality in terms of dominance., Competing Interests: Conflict of Interest: None declared., (Copyright: © 2023 by Beyoglu Eye Training and Research Hospital.)

Background: The purpose of this study was to compare corneal power and horizontal corneal diameter (white-to-white [WTW] distance) readings obtained by the Orbscan II topographer and the iTrace aberrometer.Methods: Keratometry readings in the flat (Kf) and steep (Ks) meridians and WTW distance were measured with the Orbscan II and iTrace systems in 100 myopic patients. Statistical evaluation was performed using the paired t test, Pearson correlation, and Bland-Altman analysis for comparison of measurement techniques.Results: The mean keratometry values with the Orbscan II and iTrace were 43.16 ± 1.44 and 42.64 ± 1.43 diopter (D), respectively (P < 0.0001). The mean WTW distance measurements with the Orbscan II and iTrace were 11.57 ± 0.34 and 11.33 ± 0.36 mm, respectively (P < 0.0001). For the measurement of corneal power, the 95 % limits of agreement (LoA) between the Orbscan II and iTrace were - 0.21 to 1.21 D for the flat meridian and - 0.15 to 1.25 D for the steep meridian. For the measurement of WTW distance, the range of the 95 % LoA between the two devices was 0.47 mm.Conclusions: For some clinical applications, the keratometry and WTW distance measurements obtained by the Orbscan II topographer and the iTrace aberrometer differed greatly and therefore were not interchangeable.Trial Registration: Clinical trials number: ChiCTR-OCS-14005077 (August 2nd, 2014). [ABSTRACT FROM AUTHOR]

Purpose: To analyze the refractive and keratometric stability in hyperopic astigmatic laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) during the first 6 months after surgery. Patients and methods: This retrospective cross-sectional study included 97 hyperopic eyes; 55 were treated with LASIK and 42 with PRK. Excimer ablation for all eyes was performed using the ALLEGRETTO excimer laser platform using a mitomycin C for PRK and a mechanical microkeratome for LASIK. Keratometric and refractive data were analyzed during three consecutive follow-up intervals (6 weeks, 3 months, and 6 months). The corneal topography was obtained using Scheimpflug topography, and subjective refractions were acquired by expert optometrists according to a standardized protocol. Results: After 3 months, mean keratometry and spherical equivalent were stable after LASIK, whereas PRK-treated eyes presented statistically significant (P<0.001) regression of hyperopia. In eleven cases, hyperopic regression of >1 D occurred. The optical zone diameter did not correlate with the development of regression. Conclusion: After corneal laser refractive surgery, keratometric changes are followed by refractive changes and they occur up to 6 months after LASIK and for at least 6 months after PRK, and therefore, caution should be applied when retreatment is planned during the 1st year after surgery because hyperopic refractive regression can lead to suboptimal visual outcome. Keratometric and refractive stability is earlier achieved after LASIK, and therefore, retreatment may be independent of late regression. [ABSTRACT FROM AUTHOR]

Aim: To compare the effect of pupilla dilatation on the IOLMaster keratometric values and investigate the correlation of keratometric data obtained by IOLMaster, automated keratometer and rotating Scheimpflug imaging system. Material and Methods: The right eyes of 68 healthy subjects were examined prospectively. The mean age of the subjects was 36.26±15.51 years. Keratometry measurements in the flat (K1) and steep (K2) meridians were taken with the IOLMaster in eyes with pre-dilatation and post-dilatation of the pupillas. Automated keratometer and rotating Scheimpflug imaging system measurements were obtained simultaneously, after pupil dilatation. The measurement differences between the devices were compared by analysis of variance and Friedman analysis of variance. The correlation between devices were evaluated by using Pearson correlation analysis. Results: The K1/K2 readings of the IOLMaster were 43.37/44.33 diopters in pre-dilatation and 43.38/44.32 diopters in post-dilatation. The difference between keratometric values in pre- and post-dilataion pupilla were not statistically significant (p>0.05). The K1/K2 readings of the automated keratometer and Scheimpflug imaging system were 43.35/44.18 diopters and 43.12/44.07 diopters, respectively. The difference between the values was statistically significant (p=0.0001) but the correlation among these three systems was strong (r=0.988, p<0.001 and r=0.989, p<0.001, respectively). Conclusions: IOLMaster keratometric values in pre- and post-dilatation pupillas are similar but IOLMaster keratometric values can differ from automated keratometry and Scheimpflug imaging system. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to investigate the sensitivity, specificity, and accuracy of The Cone Location and Magnitude Index (CLMI) in keratoconus diagnosis.Methods: 301 eyes of 159 keratoconus patients and 394 eyes of 265 refractive surgery candidates as a control group were enrolled in this retrospective clinical study. CLMI was compared with keratometric corneal topography parameters, wavefront aberrations, and pachymetry data derived from optical coherence tomography using independent sample t-tests and ROC curves. Logistic regression analysis was applied to determine the most accurate parameter in keratoconus diagnosis. Pearson's correlation analysis was used to determine the correlation between CLMI and the other measurements.Results: Average axial CLMI (aCLMI) was 8.19 ± 6.15 D in the keratoconus group and 0.83 ± 0.62 D in the control group (p = 0.001). aCLMI had the greatest sensitivity (89%), specificity (94%), and accuracy (92%) for the keratoconus diagnosis at the best cut-off point of 1.82 according to the ROC curve. Logistic regression analysis selected aCLMI as the most accurate measurement among the other parameters (accuracy 92.8%). aCLMI showed strongest correlations with coma-like aberrations (r = 0.881), total high-order aberrations (r = 0.858), and vertical coma (r = -0.814), respectively.Conclusion: CLMI is a robust index for screening keratoconus with high sensitivity, specificity, and accuracy. [ABSTRACT FROM AUTHOR]

Aim: To compare the outcomes of peripheral corneal relaxing incisions (PCRIs) based on standardized nomogram using keratometry from Scheimpflug and Placido machines during standard cataract surgery and to assess the astigmatism neutralization potential of PCRIs. Methods: In this prospective, comparative case series of eyes with keratometric astigmatism between 0.75D to 2.5D, undergoing routine cataract surgery, PCRIs were performed using standardized nomogram and keratometric data from either Scheimpflug or Placido machines. A single eye of 42 consecutive patients was recruited in each group. Data on pre- and postoperative uncorrected distance visual acuity (UDVA), corrected DVA (CDVA), keratometry and refraction were assessed at 10 weeks postoperatively. Refractive and keratometric J0 J45 vectors were also analyzed. Results: Data on 41 and 39 eyes were available in each group, respectively. There was a significant reduction in keratometric astigmatism in both groups. However, between Scheimpflug and Placido groups, there was no difference in postoperative logMAR UDVA [0.15 ± 0.18 vs 0.14 ± 0.16, p = 0.82] and CDVA [0.11 ± 0.11 vs 0.09 ± 0.10, p = 0.58], postoperative spherical equivalent [-0.34D ± 0.40D vs -0.50D ± 0.43D, p = 0.11], keratometric J0 [-0.03 ± 0.39 vs 0.01 ± 0.85, p = 0.67] and J45 [-0.03 ± 0.41 vs 0.01 ± 0.86, p = 0.65] and refractive J0 [0.05 ± 0.46 vs -0.03 ± 0.92, p = 0.47)] and J45 [-0.06 ± 0.49 vs -0.03 ± 0.99, p = 0.82] vectors, reduction of keratometric astigmatism [-0.40D ± 0.55D vs -0.35D ± 1.24D, p = 0.75] and the keratometric astigmatism neutralization potential [38.56 % ± 29.71 % vs 52.66 % ± 44.06 %, p = 0.12].- Conclusions: Although PCRIs performed using Scheimpflug or Placido keratometry reduced the keratometric astigmatism significantly during standard cataract surgery. The astigmatic neutralization potentials of PCRIs comparing these two groups were not significantly different and remain low during the early postoperative period. [ABSTRACT FROM AUTHOR]

To compare the precision among currently available keratometry devices. The corneal power was measured on two separate visits with the Nidek TonoRef II Autorefractor/Keratometer, the Zeiss IOLMaster 500, the Haag-Streit Lenstar LS 900, the Oculus Pentacam, and the Oculus Keratograph 4M. The precision was evaluated as the mean absolute intersession difference (MAD) between the corneal power measurements for each patient. Only the non-operated eye was included in the study. The Keratograph was found to have the highest MAD (0.215 D), which was significantly different from the other devices except for the IOLMaster. Nidek ARK had the lowest MAD (0.097 D), but this was not significant compared to Pentacam (0.124 D), Lenstar (0.132 D), or IOLMaster (0.140 D). Only one out of 29 patients had a precision difference exceeding 0.25 D with the Nidek ARK. Among the devices studied, the Nidek ARK was found to have the highest and the Keratograph was found to have to the lowest precision for the measurement of corneal power. [ABSTRACT FROM AUTHOR]

Determining an accurate central corneal power ( K) measurement is crucial for calculating the intraocular lens power in patients who are undergoing cataract extraction. The ideal method for measuring K is to use a device that works independently of the refractive surgery information. The Scheimpflug camera system offers a promising means of measuring the true corneal power after keratorefractive surgery. In this study, we investigated the accuracy of this system in measuring central corneal power after photorefractive corneal surgery by comparing it to the theoretically derived central corneal power by history method. A total of 120 eyes of 65 (35 females and 30 males) patients were included in this study. The mean change of refraction at the spectacle plane was 3.75 D, whereas the mean change of refraction at the corneal plane was 3.37 D. Using the Sirius dual-scanning corneal tomography, the mean change in corneal power was 3.96 D. No significant differences were detected between the mean post-operative corneal power measured by the Sirius tomographer and the mean change in refraction at the corneal plane calculated clinically ( P = 0.076) and the correlation was found to be high (0.913). This study suggests that Sirius dual-scanning corneal tomography offers high predictability when measuring the central 5 mm corneal power in patients who have had myopic corneal photorefractive surgery. [ABSTRACT FROM AUTHOR]

Objective: Conventional Extracapsular cataract surgery (ECCE), Manual small incision cataract surgery (MSICS), and Phacoemulsification are the three popular forms of cataract surgery in Pakistan. Common complications such as surgically induced astigmatism, hyphema and striate keratopathy are important causes of poor uncorrected visual acuity after cataract surgery and by knowing how to minimize it we can improve visual outcome of cataract surgery. Surgically induced astigmatism (SIA) is still a common obstacle for achieving excellent uncorrected visual acuity. In this study it was meant to find out that if postoperative astigmatism in MSICS and Phacoemulsification techniques is comparable than we can encourage our trainees to do MSICS because most of trainees have to serve in periphery in their early carrier where Phacoemulsification equipment is not available. To compare mean surgically induced astigmatism in Manual Small Incision Cataract Surgery and Phacoemulsification surgery. Materials & Methods: This was a randomized control trial. 214 patients were included in our study through our Out Patient Department (OPD)from 30"' May 2014 till 30th December 2014 in Khyber Institute of Ophthalmic Medical Sciences (KIOMS), Hayatabad Medical Complex, Peshawar. Informed written consent was taken from every patient. Personal bio-data was recorded on predesigned proforma. First, patients were randomly allocated to a group by lottery method and subsequent patients were alternatively allocated to other group by consecutive sampling into Phacoemulsification surgery group and manual small incision cataract surgery group. Corneal astigmatism was measured by Helmholtz keratometer (Topcon OM-4) (k values were taken in diopter). All patients were operated by two experienced using manual small incision cataract surgery technique and Phacoemulsification. Corneal astigmatism was measured pre-operatively then at 6lh week post operatively in both groups with the same keratometer. Using pre-op and 6 weeks keratometric astigmatism readings, SIA was calculated by subtraction method. Axis of astigmatism was determined by comparing K readings in diopters. K1 > K2 means with-the-rule astigmatism, K2 > K1 means against-the-rule astigmatism, while K1 = K2 means neutral astigmatism. Results: Mean age for Phacoemulsification surgery group was 61,8±4 yrs and 60.7±3.5 yrs for MSICS group. More patients were present in age group 56-60 yrs for both groups. Pre-operative mean astigmatism was 0.5240, 0.5440 for Phacoemulsification group and MSICS group respectively. Post-operative mean astigmatism was 0.792, 0.8242 for Phacoemulsification group and MSICS group respectively. P value for these astigmatism was 0.8058, 0.6922 for pre-operative and post-operative mean astigmatism respectively. Surgically induced mean astigmatism was 1.1 D±0.9 D, 1.2±0.8D for Phacoemulsification surgery group and MSICS group respectively, P=0.393, which was statistically not significant hence there was no difference in these two surgery groups. Conclusion: Manual small-incision cataract surgery is comparable to Phacoemulsification for the rehabilitation of the patient with cataract at 6 weeks. Manual small-incision cataract surgery is safe and nearly as effective. Small-incision surgery does not need the capital investment and recurring expenditure of a Phacoemulsification machine. So if we encourage our trainees to take interest in MSICS, so that their patients can enjoy early visual rehabilitation at low cost. [ABSTRACT FROM AUTHOR]

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The aim of this study is to assess the agreement of IOL power and ocular biometry measurements before and after pupillary dilatation by using the IOLMaster. This was the prospective nonrandomized cohort study. Measurements were taken with the IOLMaster (Carl Zeiss Meditec AG, Jena, Germany) from healthy volunteers at the Department of Ophthalmology, King Chulalongkorn Memorial Hospital. Axial length (AL), keratometry both flattest and steepest ( K1, K2), and anterior chamber depth (ACD) were measured before and after the dilatation of the pupil with 1 % tropicamide. The IOL power was calculated using the Sanders-Retzlaff-Kraff/Theoretical (SRK/T) formula. The mean difference of each parameter was assessed by Bland-Altman plot analysis. 384 eyes from 195 healthy volunteers were measured. The mean age of the patients was 52.39 ± 1.02 years (range 21-79). Pupillary dilatation had no significant effect on AL ( p = 0.07), keratometry [steepest K ( p = 0.95) and flattest K ( p = 0.17)], and IOL power (Alcon SN60WF) ( p = 0.40) obtained from the IOLMaster. However, ACD was significantly increased post-dilatation ( p < 0.05). The Bland-Altman plot indicated good concordance in nearly all parameters except ACD. For ACD measurements, the 95 % limit of agreement between pre-dilatation and post-dilatation was −0.47 to 0.23 mm; therefore, 92.2 % of the measurement differences were with a LoA of −0.47 to 0.23 mm. There were no eyes that could not be measured by the IOLMaster. The dilatation of the pupil had no significant effect on AL, keratometry measurements, and SRK/T calculated IOL power. However, the ACD significantly increased post-dilatation. [ABSTRACT FROM AUTHOR]

Purpose To compare anterior eye segment measurements obtained using low optical coherence reflectometry (LENSTAR LS900, Haag-Streit), autokeratometry (RC-5000, Tomey) and corneal topography (Topolyzer, Wavelight). Methods In 46 healthy subjects, flat keratometry ( K f ), steep keratometry ( K s ), mean keratometry ( K m ) and white-to-white (WTW) distance were measured by Lenstar, Tomey RC-5000 and Topolyzer. Results K f and K m measurements of Lenstar were significantly steeper than Tomey RC-5000 (both p < 0.001), but the 95% LoA of them were narrow (−0.22 to 0.46 D, −0.16 to 0.36 D, respectively). There were no significant differences between the K f and K m measurements of Lenstar and Topolyzer, with a narrow 95% LoA. There were no significant differences between the K s measurements of Lenstar and Tomey RC-5000, and Lenstar and Topolyzer. A good agreement was found between them with 95% LoA of −0.40 to 0.56 D, and −0.56 to 0.64 D, respectively. WTW measurements with Lenstar were greater than those with Tomey RC-5000 and Topolyzer ( p = 0.042, p < 0.01, respectively). A good agreement existed between the WTW obtained by Lenstar and Topolyzer, Tomey RC-5000, with 95% LoA ranging from −0.13 to 0.74 mm and −0.33 to 0.51 mm. Conclusions Generally good agreement was found between the Lenstar and Tomey RC-5000, Topolyzer for K and WTW measurements. In clinical practice, K and WTW measurements obtained by Lenstar and Tomey RC-5000, Topolyzer can be used interchangeably. [ABSTRACT FROM AUTHOR]

Objectives: To assess and document the refractive correction of astigmatism in cases of cataract, with astigmatism after Toric IOL implantation. Study Design: Interventional study. Place & Duration: Department of Ophthalmology CMH Rawalpindi. Patients & Methods: Our study included 40 eyes of 23 patients, who had cataract with corneal astigmatism ranging from 1.5 to 6.0 diopters. Visual acuities, IOP, keratometric readings, documentation of steep meridian, pachymetry and corneal topography was done to rule out progressive keratoconus and other corneal ectatic conditions. Phaco-emulsification was done by a clear corneal incision and a Toric IOL was implanted using the Acrysof Toric IOL Calculator. This study group was followed up for 06 months. Results: Post operative astigmatism was assessed after 1st week, 1st month and after 06 months. After the surgery, visual acuities improved significantly in all patients. Astigmatism was definitely reduced in all the patients. The amount of astigmatism which was observed at the end of 06 months was negligible and almost unnoticeable by the patients. Conclusion: Our study shows that Toric IOL Implants help to achieve good vision and reduced dependency on spectacles in about 75% of cases. The Toric IOL implants showed good rotational stability, if IOL rotation occurs within the first week, it can be re-positioned and give the due results in a refractive disorder. Although it is seldom required if placed correctly in the first instance. [ABSTRACT FROM AUTHOR]

Objectives The aim of this study was to compare ocular dimensions, corneal curvature, and corneal thickness between horses affected with hereditary equine regional dermal asthenia ( HERDA) and unaffected horses. Animals Five HERDA-affected quarter horses and five healthy control quarter horses were used. Methods Schirmer's tear test, tonometry, and corneal diameter measurements were performed in both eyes of all horses prior to ophthalmologic examinations. Ultrasonic pachymetry was performed to measure the central, temporal, nasal, dorsal, and ventral corneal thicknesses in all horses. B-mode ultrasound scanning was performed on both eyes of each horse to determine the dimensions of the ocular structures and to calculate the corneal curvature. Results Each corneal region examined in this study was thinner in the affected group compared with the healthy control group. However, significant differences in corneal thickness were only observed for the central and dorsal regions. HERDA-affected horses exhibited significant increases in corneal curvature and corneal diameter compared with unaffected animals. The ophthalmologic examinations revealed mild corneal opacity in one eye of one affected horse and in both eyes of three affected horses. No significant between-group differences were observed for Schirmer's tear test, intraocular pressure, or ocular dimensions. Conclusions Hereditary equine regional dermal asthenia-affected horses exhibit decreased corneal thickness in several regions of the cornea, increased corneal curvature, increased corneal diameter, and mild corneal opacity. Additional research is required to determine whether the increased corneal curvature significantly impacts the visual accuracy of horses with HERDA. [ABSTRACT FROM AUTHOR]

Purpose: To determine whether the total corneal refractive power (TCRP) value, which is based on measurement of both anterior and posterior corneal astigmatism, is effective for toric intraocular lens (IOL) calculation with AcrySof® Toric IOLs. Patients and methods: A consecutive series of cataract surgery cases with AcrySof toric IOL implantation was studied retrospectively. The IOLMaster® was used for calculation of IOL sphere, the Pentacam® TCRP 3.0 mm apex/ring value was used as the keratometry input to the AcrySof Toric IOL Calculator and the VERION™ Digital Marker for surgical orientation. The keratometry readings from the VERION reference unit were recorded but not used in the actual calculation. Vector differences between expected and actual residual refractive cylinder were calculated and compared to simulated vector errors using the collected VERION keratometry data. Results: In total, 83 eyes of 56 patients were analyzed. Residual refractive cylinder was 0.25 D or lower in 58% of eyes and 0.5 D or lower in 80% of eyes. The TCRP-based calculation resulted in a statistically significantly lower vector error (P<0.01) and significantly more eyes with a vector error <0.5 D relative to the VERION-based calculation (P=0.02). The TCRP and VERION keratometry readings suggested a different IOL toric power in 53/83 eyes. In these 53 eyes the TCRP vector error was lower in 28 cases, the VERION error was lower in five cases, and the error was equal in 20 cases. When the anterior cornea had with-the-rule astigmatism, the VERION was more likely to suggest a higher toric power and when the anterior cornea had against-the-rule astigmatism, the VERION was less likely to suggest a higher toric power. Conclusion: Using the TCRP keratometry measurement in the AcrySof toric calculator may improve overall postoperative refractive results. Consideration of measured posterior corneal astigmatism, rather than a population-averaged value, appears advantageous. [ABSTRACT FROM AUTHOR]

Purpose. To analyze visual acuity and corneal changes after combined corneal surgery for keratoconus: eximer laser photorefractive keratectomy (PRK) for partial correction of refractive error and simultaneous corneal crosslinking (CXL) for disease stabilisation. Methods. To show visual acuity change we evaluate and compare the uncorrected (UDVA) and best-corrected (BCDVA) visual acuity before, after half a year and a year after the surgery. Disease stability has been assessed by comparing the UDVA, BCDVA and maximum keratometry (Kmax) value after half a year and a year after the surgery. Results. We analyse 24 keratoconus cases, operated with combined surgery. There are 16 cases with one year postoperative data and 24 cases with half a year postoperative data. The mean patients' age was 27.14 ± 4.41 (20 to 37 years). Groups according to the stages of keratoconus (by Amsler-Krumeich classification) were the following: 7 eyes (29%) in the 1st stage of the disease, 13 eyes (54%) in the 2nd stage and 4 eyes (17%) in the 3rd stage. There was no case of the 4th stage keratoconus. A statistically reliable change of the mean UDVA was assessed during the monitoring periods (first - before the surgery: 0.3 ± 0.17, second - after half a year postop.: 0.75 ± 0.23, third - after a year postop.: 0.71 ± 0.23; Friedman's criteria: = 28.84, lls = 2, p < 0.001). There is improvement comparing the data of the first visit and the data of next visits (for both cases p < 0.001) and a stable result comparing the data of the second and third visits (p = 0.650). A statistically reliable change in the mean BCDVA was assessed during the monitoring periods (first: 0.62 ± 0.22, second: 0.83 ± 0.16, third: 0.84 ± 0.15; Friedman's criteria: = 21.11, lls = 2, p < 0.001). There is improvement comparing the data of the first visit and next visits (p = 0.006 and p = 0.001, respectively) and a stable result comparing the data of the second and third visits (p = 0.625). A statistically reliable change of the mean highest keratometric value (Kmax) was assessed during all three monitoring periods (first: 50.37 ± 2.65, second: 47.48 ± 2.41, third: 47.58 ± 2.39; Friedman's criteria: = 26.98, lls = 2, p < 0.001): decrease of the value between the first and next visits (for both cases p < 0.001), a stable value between the second and third visits (p = 0.983). There were no complications, undesirable or side effects related with the combined keratoconus surgery. Conclusions. PRK combined with simultaneous CXL surgery keeps and improves preoperative visual acuity, halts the progression of keratoconus. It normalizes the central optical zone of the cornea, reduces the keratoconus induced refractive error, and results in easier and more precise spectacle or contact lens prescription. This procedure reduces the need for penetrating corneal transplantation. Further monitoring of keratoconus patients in order to assess the longterm effect and safety is needed. [ABSTRACT FROM AUTHOR]

Objectives To investigate the influence of full scleral lenses on corneal curvature and pachymetry in keratoconus patients. Methods In this intervention study, 20 eyes of 14 patients were measured by Scheimpflug imaging (Pentacam HR, Oculus) at two time points: directly and ≥1 week after scleral lens removal. Steep, flat and maximal keratometry ( K steep , K flat and K max ) and optical pachymetry were analyzed. A generalized estimating equation analysis was performed to correct for paired eyes. Results Directly after scleral lens removal, all three curvature parameters were significantly flatter compared to ≥1 week after scleral lens removal. Average K steep was 0.7 diopter (D) lower ( P < 0.001), average K flat was 0.5 D lower ( P = 0.037) and average K max was 1.1 D lower ( P < 0.001). Directly after scleral lens removal, average optical pachymetry was ±2.5% higher ( P < 0.001) compared to ≥1 week after scleral lens removal. Conclusions Although scleral lenses do not mechanically touch the cornea, curvature and pachymetry seem to be influenced by scleral lens wear in keratoconus patients. The duration of these changes remain unclear. [ABSTRACT FROM AUTHOR]

Purpose: To compare the astigmatic power of toric intraocular lenses (IOLs) obtained from the AcrySof, TECNIS, and iTrace toric calculator in patients with pre-operative with-the-rule (WTR) or against-the-rule (ATR) corneal astigmatism. Materials and Methods: Fifty eyes with cataract and corneal astigmatism greater than 0.75 diopters were enrolled in each group (WTR and ATR). Keratometric values were measured using autokeratometry, an IOLMaster, and an iTrace, which incorporated corneal topography and ray-tracing aberrometry. Based on measured keratometric values, the astigmatic power of each toric IOL was calculated using three toric calculators. Results: Bland-Altman plots showed good agreement between six pairwise corneal astigmatism values in both groups. The TECNIS calculator tended to suggest a higher astigmatic power of the toric IOL than the AcrySof calculator. With the higher astigmatism and keratometric values from the IOLMaster, in both groups, calculations from the AcrySof and TECNIS calculators resulted in higher calculated astigmatic powers than those from same calculators with autokeratome-try-measured values, demonstrating good agreement. With the higher calculated astigmatic power values, the values from the iTrace toric calculator using keratometric values obtained from iTrace ray tracing wavefront aberrometry or iTrace simulated keratometry showed fair to moderate agreement with those from the other calcula-tor-keratometry pairs in both groups. Conclusion: To achieve the best refractive outcome after toric IOL implantation, understanding the differences in keratometric values between instruments and in calculated astigmatic power among toric calculator programs is necessary. Moreover, systemic analysis of each toric calculator in conjunction with postoperative data is required. [ABSTRACT FROM AUTHOR]

Purpose A recent threefold increase in laser treatment for advanced retinopathy of prematurity ( ROP) triggered a nationwide preschool ophthalmic and developmental status among extremely preterm survivors. Here, we discuss refraction and visual acuity. Methods Survivors ( n = 178) from a national birth cohort (February 2004 to March 2006) of gestational age <28 weeks ( PT) and 56 full-term ( FT) controls attended for evaluation at age 4 years. Cycloplegic refraction and keratometry were achieved by Retinomax autokeratorefractor and visual acuities by symbol recognition ( HOTV, log MAR). Results The refractive distribution presented a myopic tail (4.5%) and a hyperopic tail (11.9% ≥+2.5 D) as special preterm features, and corneas were more curved. Astigmatism and anisometropia were only marginally increased, and visual acuities were generally good. Best-corrected binocular median log MAR visual acuity was 0.1 in FT and 0.2 in PT, in Snellen equivalents 0.8 and 0.63. Snellen acuity ≤0.5 occurred across the ROP subgroups, but mainly in those with at least ROP stage 3. Two children had low vision. Conclusions The overall fair outcome for refraction and function is in accordance with other recent northern Europe experience. The results differ in particular from the poorer ophthalmic outcomes reported in the pioneer US treatment studies (cryotherapy for ROP and ETROP). The diode laser ablations ( n = 32) appeared effective in our series; except one child, all treated subjects had good or fair social vision at the age of 4 years. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to assess the effects of incorporating individual ocular biometry measures of corneal curvature, refractive error, and axial length on scan length obtained using Spectralis spectral domain optical coherence tomography (SD-OCT). Methods: Two SD-OCT scans were acquired for 50 eyes of 50 healthy participants, first using the Spectralis default keratometry (K) setting followed by incorporating individual mean-K values. Resulting scan lengths were compared to predicted scan lengths produced by image simulation software, based on individual ocular biometry measures including axial length. Results: Axial length varied from 21.41 to 29.04 mm. Spectralis SD-OCT scan lengths obtained with default-K ranged from 5.7 to 7.3 mm, and with mean-K from 5.6 to 7.6 mm. We report a stronger correlation of simulated scan lengths incorporating the subject's mean-K value ( ρ = 0.926, P < 0.0005) compared to Spectralis default settings ( ρ = 0.663, P < 0.0005). Conclusions: Ocular magnification appears to be better accounted for when individual mean-K values are incorporated into Spectralis SD-OCT scan acquisition versus using the device's default-K setting. This must be considered when taking area measurements and lateral measurements parallel to the retinal surface. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the predictability of the refractive correction achieved with a positional accommodating intraocular lenses (IOL) and to develop a potential optimization of it by minimizing the error associated with the keratometric estimation of the corneal power and by developing a predictive formula for the effective lens position (ELP). Materials and Methods: Clinical data from 25 eyes of 14 patients (age range, 52-77 years) and undergoing cataract surgery with implantation of the accommodating IOL Crystalens HD (Bausch and Lomb) were retrospectively reviewed. In all cases, the calculation of an adjusted IOL power (PIOLadj) based on Gaussian optics considering the residual refractive error was done using a variable keratometric index value (nkadj) for corneal power estimation with and without using an estimation algorithm for ELP obtained by multiple regression analysis (ELPadj).PIOLadj was compared to the real IOL power implanted (PIOLReal, calculated with the SRK-T formula) and also to the values estimated by the Haigis, HofferQ, and Holladay I formulas. Results: No statistically significant differences were found between PIOLReal and PIOLadj when ELPadj was used (P = 0.10), with a range of agreement between calculations of 1.23 D. In contrast, PIOLReal was significantly higher when compared to PIOLadj without using ELPadj and also compared to the values estimated by the other formulas. Conclusions: Predictable refractive outcomes can be obtained with the accommodating IOL Crystalens HD using a variable keratometric index for corneal power estimation and by estimating ELP with an algorithm dependent on anatomical factors and age. [ABSTRACT FROM AUTHOR]

Background: Objective measurement of corneal densitometry (CD) values can be used to assess corneal transparency and health status, to investigate corneal diseases, and to review anterior segment surgeries. However, literature regarding the association between CD and corneal parameters in healthy adolescent and older individuals is limited. This study investigated age-related changes in Scheimpflug CD values and their correlations with age, sex, and corneal topographic parameters., Methods: This retrospective cross-sectional observational study included 347 eyes from 181 consecutive healthy Chinese participants aged between 5 and 90 years. They were divided into 9 age groups: 5-9, 10-19, 20-29, 30-39, 40-49, 50-59, 60-69, 70-79, and 80-90 years. CD and corneal topographic measurements were measured using the Oculus Pentacam. To evaluate CD, the cornea was divided into 3 layers according to depth (anterior 120 µm, central, and posterior 60 µm), and into 4 annular regions according to diameter (0-2, 2-6, 6-10, and 10-12 mm)., Results: CD across different depths and regions was positively correlated with age (all P values <0.001). Of the 3 layers of corneal thickness, CD was highest in the anterior 120 µm and lowest in the posterior 60 µm (all P values <0.05). Among the 4 annular regions spanning the corneal diameter, the lowest CD values were 6-10, 2-6, and 0-2 mm at 5-29, 30-69, and 70-89 years, respectively. The highest CD values were 10-12 mm at 5-79 years, and 6-10 mm at 80-90 years (all P values <0.05). CD values of 10-12 mm in the anterior 120 µm corneal layer were significantly lower in men than in women (Z=-2.353; P=0.019). CD of 0-10 mm in each layer was not significantly different between sexes (all P values >0.05). Corneal topographic measurements, including flat-axis keratometry (K1), steep-axis keratometry (K2), and spherical aberration, were slightly positively correlated with age and CD (all P values <0.05). However, central corneal thickness (CCT) and thinnest corneal thickness (TCT), and age or CD showed no correlation (all P values >0.05)., Conclusions: With age, CD, keratometry, and spherical aberration gradually increased, while the corneal thickness did not change significantly., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-22-486/coif). The authors have no conflicts of interest to declare., (2023 Quantitative Imaging in Medicine and Surgery. All rights reserved.)

Purpose: To estimate the postoperative astigmatism after small-incision cataract surgery (SICS) done by junior residents at the end of 1 and 3 months., Methods: This observational longitudinal study was conducted at the Department of Ophthalmology of a tertiary eye care hospital and research center. 50 patients enrolled in the study underwent manual small incision cataract surgery by junior residents. Preoperative detailed ocular examination was done, which included keratometric estimation using autokeratometer (GR-3300K). Incision length, distance of incision from the limbus, and type of suturing technique were noted. Postoperatively, keratometric readings were noted at 1 and 3 months. Astigmatism (surgically induced astigmatism [SIA]) was estimated using Hill's SIA calculator version 2.0. All the analyses were performed using Statistical Package for the Social Sciences (SPSS) ver. 26.0 (IBM Corp., USA) software, and the statistical significance was tested at a 5% level., Results: Out of 50 patients, 54% had SIA between 1.5 and 2.5 D and 32% had SIA of more than 2.5 D. Only 14% had SIA less than 1.5 D at the end of 1 month. While 52% had SIA between 1.5 and 2.5 D, 22% had SIA between 1.5 and 2.5 D and 26% had SIA less than 1.5 D at the end of 3 months., Conclusion: The SIA in most of the SICS done by junior residents was above 1.5 D. It depended mainly on the incision length, its distance from the limbus, and the suturing technique., Competing Interests: None

Purpose: The purpose of this study was to find the incidence of refractive surprise in patients of cataract with primary pterygium and compare it with patients of cataract without pterygium after phacoemulsification surgery., Methods: The present observational study included 30 patients who had cataract with pterygium and 30 patients of cataract without pterygium. A detailed ophthalmic examination was done in all the cases. Horizontal corneal encroachment of pterygium from the limbus was measured. Keratometry and biometric measurements were performed preoperatively to determine the target refraction which was kept between - 0.50D and + 0.50D. The achieved spherical equivalent (SE) and prediction error were calculated postoperatively. A difference of >± 1.00D SE from the targeted postoperative refraction was considered a refractive surprise., Results: The mean age of patients was 61 ± 8.32 years. The mean extension of pterygium on the cornea was 2.3 ± 0.91 mm. Refractive surprise was seen in 16.7% of cases of cataract with pterygium and 10% of cases of cataract without pterygium., Conclusion: Only cataract surgery can be performed in patient having cataract with primary pterygium of up to 2.3 ± 0.91 mm horizontal corneal length, and the incidence of refractive surprise in these cases is comparable to that in patients of cataract without pterygium., Competing Interests: There are no conflicts of interest., (Copyright: © 2023 Saudi Journal of Ophthalmology.)

Background This study aimed to evaluate consecutive measurements of biometric parameters, age, and refraction in a cohort of Turkish primary school-age children and to assess the correlation between biometric changes and refraction. Methodology The study population was seven and 12-year-old children (n = 197). The retrieved data consisted of three consecutive measurements with a one-year interval for each subject. Data from one eye (right) were used. Age, gender, body mass index, spherical equivalent (SE), axial length (AL), anterior chamber depth (ACD), central corneal thickness (CCT), keratometry (K), and lens thickness (LT) were analyzed. The onset and final data were retrieved from the database in 2013 and 2016, respectively. Statistically, logistic and Cox regression models of all parameters were analyzed, and the significance level was set at 5%. Results The median of the onset and final SE values were -0.00 D (0.00-0.00) and 0.50 D (0.19-1.00), respectively. The onset AL (hazard ratio (HR) = 5.82, 95% confidence interval (CI) = 3.45-9.76, β = 1.76, p < 0.001), K mean  (HR = 2.28, 95% CI = 1.67-3.11, β = 0.82, p < 0.001), and age (HR = 0.77, 95% CI = 0.59-0.99, β = -0.26, p = 0.046) were correlated with myopia progression. To calculate the estimated SE, the onset data were included in the logistic regression model. The onset SE (β = 0.916, p < 0.001), AL (β = -0.451, p < 0.001), ACD (β = 0.430, p = 0.005), and K (β = -0.172, p < 0.001) were correlated with the mean final SE. An equation was generated using the regression model analysis. Conclusions The onset parameters of SE, AL, ACD, and K were confirmed to correlate with the final SE values in the proposed model. To confirm the use of the refractive calculator, a cross-validation analysis is needed to estimate three-year subsequent refractive error among seven and 12-year-old children., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2023, Tuncer Orhan et al.)

Purpose: This review aims to evaluate and simplify the recent literature on preoperative surgical planning, intraoperative considerations, postoperative surprises, and their management in patients with keratoconus undergoing cataract surgery., Methods: A review of the literature was done to analyze all the pertinent articles on Keratoconus and cataract surgery., Results: The surgical planning of cataracts in eyes with keratoconus needs a multifaceted approach. Preoperatively, techniques such as cross-linking or the use of intra-corneal rings help stabilize the progression. Unreliable biometric measurements are a significant problem in keratoconus patients, especially in an advanced stage of the disease. It is better to consider actual K readings if the K value is less than 55D but for a K value, more than 55D using standard K values will prevent postoperative refractive surprises. For calculation of K values, an elevation-based device like pentacam gives better repeatability in mild to moderate cases whereas for advanced keratoconus none of the keratometers is reliable. Recently, the Kane keratoconus formula performed better in all stages of disease whereas previous studies showed good results with SRK/T formula is a mild and moderate disease. Monofocal intraocular lenses are a better choice in these patients. Toric lenses can be used in mild and stable keratoconus. Intraoperatively, the use of a customized RGP lens can overcome the challenge of image distortion and loss of visual perspective. Despite taking necessary measures, postoperative refractive surprise can occur and can be managed with IOL exchange or Secondary IOLs., Conclusion: There is a spectrum of challenges in managing cataracts in keratoconus which makes thorough preoperative planning important for good surgical outcomes. Despite the measures, there might be post-operative surprises and the patients need to be informed regarding the same.

Introduction: This is a cross-sectional cohort study focused on assessing the influence of ocular biometric parameters of different camera devices for accurately predicting the intraocular lens (IOL) power in congenital ectopia lentis (EL) patients., Methods: This study includes a total of 91 eyes of 60 patients with congenital EL from June 2018 to April 2021. All patients underwent lens subluxation surgery with Cionni modified capsular tension rings implantation. Ocular parameters measured by partial coherence interferometry (IOLMaster 700; Carl Zeiss Meditec AG, Jena, Germany) and rotating Scheimpflug camera (Pentacam HR system; Oculus Optikgeräte GmbH, Wetzlar, Germany) were acquired from the database. The authenticity of the different keratometries (Ks) was analyzed by comparing the prediction error in spherical equivalent under controlled formula SRK/T, Haigis, and after Wang-Koch (WK) adjustment., Results: We observed significant greater K values were obtained in IOLMaster than Pentacam, resulting in more significant hyperopia error while calculating SRK/T. The IOL power calculated with the total corneal refractive power (TCRP) from Pentacam revealed the highest prediction accuracy, indicating that TCRP is the closest to the actual refractive power of the cornea. However, in an exceptional case for long eye patients, total K from IOLMaster was better recommended when using formula Haigis with WK adjustment., Conclusions: For most instances, TCRP is the best-recommended source of K value while calculating IOL power for EL patients. However, the total K from IOLMaster preferably fits for long eye patients, who require WK adjustment for Haigis formula., (© 2022 The Author(s). Published by S. Karger AG, Basel.)

Purpose: To investigate the alterations in biometric parameters among Chinese adolescents over an extended period of wearing orthokeratology lenses, as well as the subsequent changes after a one-month cessation of lens usage prior to the secondary lens fitting., Methods: Twenty-four myopic patients aged 7-14 were enrolled in this 37-month prospective observational study. Ocular biometric parameters were measured in the study. Ocular biometric parameters were assessed, and the utilization of Generalized Estimating Equations (GEE) was employed in the analysis to address the correlation between the two eyes of each participant., Results: The axial length (AL) increased by 0.55 mm after 36 months of lens wearing and further increased to 0.62 mm at the 37-month follow-up compared to the initial measurement. The differences in AL elongation per month between the 37-month time point and the 12-, 24-, and 36-month marks of lens wearing were found to be statistically significant (p 12-month = 0.001; p 24-month = 0.003; p 36-month = 0.001). Following the cessation of lens wear for 1 month, there was no significant complete recovery observed in the flat and steep keratometry values. However, the intraocular pressure and anterior chamber depth returned to their baseline levels., Conclusions: The AL elongation undergoes alterations during temporary discontinuation of lenses, with the flat and steep keratometry measurements remaining significantly flatter compared to the baseline. However, the intraocular pressure and anterior chamber depth return to their initial levels after one month of lens cessation.

Purpose To evaluate how soft lens power affects rigid gas-permeable (RGP) lens power and visual acuity (VA) in piggyback fittings for keratoconus. Methods Sixteen keratoconus subjects (30 eyes) were included in the study. Piggyback contact lens fittings combining Senofilcon-A soft lenses of −6.00, −3.00, +3.00 and +6.00 D with Rose K2 RGP contact lenses were performed. Corneal topography was taken on the naked eye and over each soft contact lens before fitting RGP lenses. Mean central keratometry, over-refraction, RGP back optic zone radius (BOZR) and estimated final power as well as VA were recorded and analyzed. Results In comparison to the naked eye, the mean central keratometry flattened with both negative lens powers ( p < 0.05 in all cases), did not change with the +3.00 soft lens power ( p = 1.0); and steepened with the +6.00 soft lens power ( p = 0.02). Rigid gas-permeable over-refraction did not change significantly between different soft lens powers (all p > 0.05). RGP's BOZR decreased significantly with both positive in comparison with both negative soft lens powers (all p < 0.001), but no significant differences were found among negative- or positive-powers separately (both p > 0.05). Estimated RGP's final power increased significantly with positive in comparison with negative lens powers (all p < 0.001), but no significant differences were found among negative or positive lens powers separately (both p > 0.05). Visual acuity did not change significantly between the different soft lens powers assessed (all p > 0.05). Conclusion The use of negative-powered soft lenses in piggyback fitting reduces RGP lens power without impacting VA in keratoconus subjects. [ABSTRACT FROM AUTHOR]

Purpose: The purpose was to evaluate and compare the visual and refractive outcomes, topographic keratometry (K) and complications of Intacs and Intacs SK for mild to moderate keratoconus. Methods: In this retrospective study, all mild to moderate keratoconus eyes that underwent implantation of Intacs (Intacs group) or Intacs SK (Intacs SK group) with minimum follow-up of 12 months were included. Preoperative and postoperative uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction, manifest cylinder, spherical equivalent (SE), minimum topographic keratometry, maximum topographic keratometry, and average topographic keratometry were compared in both groups. Results: There were 16 eyes in the Intacs group and 18 eyes in the Intacs SK group. Preoperatively, both groups were comparable for most parameters except gender and minimum K and average K. At 6 months postoperatively there were statistically significant improvements in UDVA, CDVA, manifest sphere, SE, minimum K, maximum K, and average K (P < 0.05, all comparisons). Manifest cylinder improved at 6 months, but the improvement was not statistically significant (P > 0.05). The outcomes remained stable with no statistically significant differences between the 6 and 12 months visits. There were no complications in both groups. Conclusion: Both models of Intacs significantly improved vision and refractive outcomes, and topographic keratometry in cases of mild to moderate keratoconus. Intacs SK provided better (not statistically significant) results. [ABSTRACT FROM AUTHOR]

Purpose: Beyond in-vivo histological analysis of retinal tissue, optical coherence tomography (OCT) allows quantitative image analysis. This study evaluates associations of macular retinal thickness measured with spectral-domain OCT (SD-OCT) and ocular and systemic cardiovascular parameters in adult subjects. Methods: An epidemiological cross-sectional study was performed in the staff of a European high-tech company. Examination of known cardiovascular risk factors including biochemical blood analysis was performed, and ocular parameters such as refraction, tonometry, SD-OCT imaging of the macula and cornea, and fundus photography were evaluated. Retinal thickness measurements were evaluated according to the ETDRS grid. Associations of macular retinal thickness and systemic cardiovascular and ocular parameters were calculated by multivariate analysis using SPSS software. Results: Four hundred and twenty-four probands were included. Macular thickness measurement were significantly associated with gender and refraction. Female persons had thinner retinal thickness in all zones. Macular thickness decreased with increasing myopia in all perifoveal measurements. Outer perifoveal measurements were associated with keratometry; a flatter corneal radius was linked to a thinner retina. Tonometry and systemic cardiovascular risk factors were not associated with macular retinal thickness in multivariate analysis ( p > 0.05). Conclusions: Macular retinal thickness is associated with refraction and gender; cardiovascular risk factors or tonometry do not influence macular retinal thickness measurements. Keratometry might influence outer zone measurements. Our findings provide a dataset for quantitative evaluation of SD-OCT, and evaluate influencing factors. [ABSTRACT FROM AUTHOR]

Background: Few, and inconsistent, studies have showed high heritability of some parameters of the anterior segment of the eye; however, no heritability of anterior chamber volume (ACV) has been reported, and no study has been performed to investigate the correlation between the ACV and central corneal thickness (CCT). Methods: Anterior segment measurements (Pentacam, Oculus) were obtained from 220 eyes of 110 adult Hungarian twins (41 monozygotic and 14 same-sex dizygotic pairs; 80% women; age 48.6 ± 15.5 years) obtained from the Hungarian Twin Registry. Results: Age- and sex-adjusted heritability of ACV was 85% (bootstrapped 95% confidence interval; CI: 69% to 93%), and 88% for CCT (CI: 79% to 95%). Common environmental effects had no influence, and unshared environmental factors were responsible for 12% and 15% of the variance, respectively. The correlation between ACV and CCT was negative and significant (rph = −0.35, p < .05), and genetic factors accounted for the covariance significantly (0.934; CI: 0.418, 1.061) based on the bivariate Cholesky decomposition model. Conclusion: These findings support the high heritability of ACV and central corneal thickness, and a strong genetic covariance between them, which underscores the importance of identification of the specific genetic factors and the family risk-based screening of disorders related to these variables, such as open-angle and also angle closure glaucoma and corneal endothelial alterations. [ABSTRACT FROM PUBLISHER]

Background The aim was to determine the agreement in keratometric readings measured with the Biograph/LENSTAR, the Pentacam and an auto-kerato-refractometer in a 40- to 64-year-old population. Methods This report is part of the first phase of the population-based Shahroud Cohort Eye Study. In virgin eyes, agreement among keratometry readings of three devices was examined in 7,260 eyes using the Bland-Altman method. The inter-device 95 per cent limits of agreement (95% LoA) and 95% confidence interval for upper and lower limits of agreement were calculated. Comparisons were made for keratometric readings of the flat and steep meridians as maximum keratometry (max-K), minimum keratometry (min-K) and their average (mean-K). Results Based on Biograph/LENSTAR measurements, averages of max-K, min-K and mean-K were 44.70 ± 1.64, 43.87 ± 1.54 and 44.28 ± 1.58 D, respectively. The quantile-quantile plot revealed that all three variables had normal distributions in this population. Agreement between the Biograph/LENSTAR and the auto-kerato-refractometer (max-K difference: -0.03 D, 95% LoA: -0.81 to 0.75; min-K difference: -0.08 D, 95% LoA: -0.85 to 0.68) was better than the agreement between the Biograph/LENSTAR and the Pentacam (max-K difference: 0.50 D, 95% LoA: -3.24 to 4.25; min-K difference: 0.59 D, 95% LoA: -3.00 to 4.17). The agreement between the Pentacam and the auto-kerato-refractometer (max-K difference: 0.54 D, 95% LoA: -3.16 to 4.24; min-K difference: 0.66 D, 95% LoA: -0.77 to 0.53) was worse than the other two pairs. Conclusion These three devices are not interchangeable in terms of keratometry for calculation of the intraocular lens power. Agreement between the Biograph/LENSTAR and the auto-kerato-refractometer can be increased with regression models but this is not true in case of Biograph/LENSTAR and Pentacam. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine and compare the repeatability of keratometry measurements with the Javal manual keratometer, Topcon automated kerato-refractometer, IOLMaster, EyeSys Corneal Analysis System, and Pentacam Scheimpflug Topography System, and determine the agreement of measurements of the latter four devices with the Javal keratometer as the gold standard. In this cross-sectional study, 21 people with no history of ocular disease or surgery were examined twice with each device. Minimum, maximum, and average keratometry readings were recorded in diopters (D) for each eye and used in the analyses. For statistical analysis, we determined correlation coefficients and used the Bland-Altman method and calculated the 95 % limits of agreement (LoA). All repeatability coefficients were satisfactorily high. Best repeatability for minimum keratometry and maximum keratometry readings was seen with IOLMaster (95 % LoA −0.23 to 0.19 D and −0.31 to 0.32 D, respectively). Agreement with Javal manual keratometry was best with Topcon and IOLMaster for minimum keratometry readings (95 % LoA −0.67 to 0.28 D and −0.57 to 0.38 D, respectively), and with Topcon for maximum keratometry readings (95 % LoA −0.85 to 0.63 D). In our series of normal eyes, keratometry readings with Topcon, IOLMaster, and Pentacam showed very good agreement with Javal measurements, and inter-device agreements were better than the repeatability of the manual gold standard. However, differences between Javal and EyeSys may not be clinically acceptable, and these two devices should not be used interchangeably. Further studies are needed to investigate these issues in non-virgin eyes. [ABSTRACT FROM AUTHOR]

Purpose: To compare keratometry, astigmatism and axis values with different instruments in cataract patients and to assess the agreement and correlation between these devices. Materials and Methods: 62 eyes of 62 cataracts patients (37 men, 25 women) with a mean age of 64±11 years (41-84) were included in the study. Keratometry, astigmatism, axis values of the patients were analysed with autokeratometer, IOL master and Pentacam and The difference, agreement and correlation between the devices were compared statistically. Results: Keratometry values were 43.41±1.58 D (39.75-47.25D), 43.54±1.56 D (39.8-47.44 D), and 43.25±1.61 D (39.1047.10 D), astigmatism values were 0.93±0.93 D (0-4.50 D), 1,10 ±1.08 D (0.23-5.57 D), 0.96±1.00D (0.10-4.40 D) and axis values were 78.250+61.760 (0-1800), 96.290±59.360 (5-1800), 86.220±56.170 (1.00-1750) for autokeratometer, IOL master and Pentacam, respectively. Keratometry and astigmatism values measured with these 3 devices showed good agreement, correlation and repeatability (interclass correlation coefficients for all the values above 0.90). However, the relationship in axial location values were found to be weaker (interclass correlation coefficients values below 0.90). Conclusion: Keratometry and astigmatism measured with these three devices show good agreement, correlation and repeatbility. However, axis location values were weaker compared to other measurements. Therefore, the axis values measured with these devices should not be used interchangably. [ABSTRACT FROM AUTHOR]