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Background: Repeatability and validity are important components of precision in any measurement system. Aim: This study aimed to determine the effect of change in head and neck position and body posture on the repeatability of intraocular pressure (IOP) measurements with PT-100 noncontact tonometer and compare with Goldmann, PT-100 and Schi⊘tz tonometer readings. Setting: Optometry clinic, Saudi Arabia. Methods: The IOP was measured in one selected eye of 84 healthy participants (mean aged 21.9 ± 2.0 years) using PT-100 in three head and body positions, Goldmann tonometer and Schi⊘tz on two separate visits, in a randomised fashion. Central corneal thickness (CCT) was measured using an ultrasound pachymeter. The repeatability, agreement and correlations between CCT and IOP differentials were assessed. Results: The IOP measured in three head and body positions with the PT-100 were similar and comparable to Goldmann IOPs in sessions one and two with 74% and 86% of PT-100 measurements within ±3 mmHg of the Goldmann tonometry, respectively, for sessions one and two. The Schi⊘tz tonometer-measured IOP was higher than the Goldmann IOPs (p < 0.05) with 60% and 44% of Schi⊘tz IOPs within ±3 mmHg of the Goldmann tonometer IOP in sessions one and two, respectively. The limits of repeatability and reproducibility were best with the PT-100 and worst with the Schi⊘tz tonometer. The mean CCT (552±36 µm) was negatively correlated with differences between Goldmann and both PT-100 and Schi0tz-measured IOP. Conclusion: Postural changes did not affect the validity and repeatability of PT-100 readings. PT-100 measurements were interchangeable with Goldmann tonometer. Schi⊘tz overestimated Goldmann IOP in thicker corneas more than the PT-100.

Charlotte Laurent,1,2 Sheng Chiong Hong,3,4 Kirsten R Cheyne,2 Kelechi C Ogbuehi2 1Ophthalmology Department, Southern District Health Board, Dunedin, New Zealand; 2University of Otago, Dunedin, New Zealand; 3Ophthalmology Department, Mid Central District Health Board, Palmerston North, New Zealand; 4oDocs Eye Care Limited, Auckland, New ZealandCorrespondence: Charlotte LaurentOphthalmology Department, Dunedin Public Hospital, 201 Great King Street, Dunedin 9016, New ZealandTel +64 21 265 4347Email charlotteclairelaurent@gmail.comPurpose: Spontaneous venous pulsation (SVP) has a high negative predictive value for raised intracranial pressure and is a useful sign when assessing patients with headache. The objective was to determine if smartphone-based video ophthalmoscopy can detect SVP.Patients and Methods: In total 233 patients and 291 eyes were recruited from the Dunedin Hospital eye clinic from July to November 2018. Patients were examined by a clinician and graded for SVP with a slit lamp and 78 Dioptre lens. Videos were taken with a smartphone ophthalmoscope and graded by two separate clinicians blinded to the slit lamp findings.Results: Only 272 eyes of 215 patients were included, as others failed in the inclusion criteria for overall video quality. Sensitivity was calculated as how likely the presence of SVP on video was indicative of the presence of SVP on slit lamp. Sensitivity was 84.77% for Observer 1, with 128 videos graded as positive for SVP on video ophthalmoscopy of the 151 identified as positive on slit lamp examination. Sensitivity was 76.82% for Observer 2 with 116 videos correctly identified. The false positive rate was calculated as the number of videos graded positive for SVP that had been graded as negative on slit lamp examination. This was 10.74% for observer 1 and 31.40% for observer 2.Conclusion: This study demonstrates that SVP is detected by video ophthalmoscopy. This may be a useful triage, telemedicine and referral tool to be used for p

Purpose: Intraocular pressure (IOP) is important in the diagnosis and management of glaucoma and remains the most significant, and only modifiable, risk factor for the development and/or progression of glaucoma. Investigators have used different techniques for IOP measurement including: Non-contact (PT100), indentation (a resurgence in Schoitz tonometry ST) and the Gold standard, Goldman applanation (GAT) tonometers. These techniques are affected by changes in head and body position and differ between individuals. To date, no study has investigated the repeatability of such postural change on IOP using different devices. This study determined the effects of change in head/neck and body posture on IOP measured with three devices. Methods: Tonometric measurements of 84 healthy subjects (mean age 21.9 ± 2.0 yrs; range, 19 to 29 years) was taken on two visits. PT100 was used to assess IOP, in a randomized fashion, in three head/body positions (HBPs), followed by GAT and ST, with a 15-minute wait period between measurements of GAT and ST. Outcome measures were IOP, limits of repeatability (LoR) and limits of agreement (LoA). The IOPs were separated into ‘high’ and ‘low’ subgroups to further assess agreement. Results: IOP measured in 3 HBPs were similar. The PT100 returned IOP measurements that were comparable to GAT IOP in both sessions with 74% and 86% of its measurements within ±3mmHg of the GAT IOP, in sessions 1 and 2, respectively. The ST IOPs were higher than the GAT measured IOPs in sessions one (p < 0.05) and two (p < 0.001) with 60% and 44% of its measurements within ±3mmHg of the GAT IOP in sessions 1 and 2, respectively. The LoR within and between sessions were best with the PT100 and worst with the ST. The ST IOP was in agreement with the GAT IOP only in subjects with IOP above 18 mmHg. Conclusions: Postural changes had no influence on the measured IOP with all three devices. The PT100 noncontact tonometer measured IOP was valid, repeatable and comparab

Kelechi C Ogbuehi, Uchechukwu L OsuagwuOutpatient Clinic, Department of Optometry, King Saud University, Riyadh, Kingdom of Saudi ArabiaBackground: The purpose of this study was to assess the repeatability and limits of agreement of corneal thickness values measured by a high-frequency ultrasound (Artemis-2), hand-held ultrasound pachymeter (DGH-500) and a specular microscope (SP-3000P).Methods: Central corneal thickness (CCT) was analyzed in this prospective randomized study that included 32 patients (18 men and 14 women) aged 21–24 years. Measurements were obtained in two sessions, one week apart, by two examiners with three devices in a randomized order. Nine measurements were taken (three with each device) on one randomly selected eye of each patient in each measurement session. The coefficient of repeatability and interobserver reproducibility for the values of each method were calculated. The limits of agreement between techniques were also evaluated.Results: There were no significant differences in CCT values between sessions for each of the three devices (P > 0.05). The repeatability coefficients for the Artemis-2 (±8 µm/±9 µm) were superior to those of the SP-3000P (±9 µm/±11 µm) and DGH 500 (±12 µm/±12 µm) in session 1/session 2 respectively, while the interobserver reproducibility index (differences between session 1 and session 2) was superior for the SP-3000P (±17 µm) with respect to DHG-500 (±29 µm) and the Artemis-2 (±31 µm). In session 1 and session 2, the limits of agreement between the techniques were 35 µm to -31 µm and 34 to -20 µm, respectively, for DGH-500 versus Artemis-2, 73 µm to 3 µm and 60 µm to 9 µm for Artemis-2 versus SP-3000P, and 58 µm to 22 µm

Kelechi C OgbuehiCornea Research Chair, Department of Optometry and Vision Sciences, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi ArabiaBackground: The intraocular pressures and biomechanical parameters measured by the ocular response analyzer make the analyzer a useful tool for the diagnosis and management of anterior segment disease. This observational study was designed to investigate the effect of topical anesthesia on the parameters measured by the ocular response analyzer: corneal hysteresis, corneal resistance factor, Goldmann-correlated intraocular pressure (IOPg), and corneal-compensated intraocular pressure (IOPcc).Methods: Two sets of measurements were made for 78 eyes of 39 subjects, approximately 1 week apart. In session 1, each eye of each subject was randomized into one of three groups: polyvinyl alcohol (0.5%), tetracaine hydrochloride (0.5%), or oxybuprocaine hydrochloride (0.4%). In session 2, eyes that were in the polyvinyl alcohol group in session 1 were assigned to the tetracaine group, those in the tetracaine group in session 1 were assigned to oxybuprocaine group, and those in the oxybuprocaine group in session 1 were assigned to the polyvinyl alcohol group. For both sessions, each subject first had his or her central corneal thickness assessed with a specular microscope, followed by measurements of intraocular pressure and corneal biomechanical parameters with the Ocular Response Analyzer. All measurements were repeated for 2 minutes and 5 minutes following the instillation of either polyvinyl alcohol, tetracaine, or oxybuprocaine. The level of statistical significance was 0.05.Results: Polyvinyl alcohol, tetracaine hydrochloride, and oxybuprocaine hydrochloride had no statistically significant (P > 0.05) effect on any of the biomechanical parameters of the cornea. There was no statistically significant effect on either IOPg (P > 0.05) or IOPcc (P > 0.05) 2 minutes after the eye drops were inst

Turki M Almubrad, Uchechukwu L Osuagwu, Ibrahim AlAbbadi, Kelechi C OgbuehiCornea Research Chair, Department of Optometry, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi ArabiaAim: To compare the precision of the Topcon SP-3000P noncontact specular microscope (NCSM) and the DGH 500 ultrasound pachymeter (USP).Methods: Triplicate measurements of central corneal thickness (CCT) for 100 eyes were taken with an NCSM and a USP in 2 visits separated by 1 week. Repeatability was assessed by computing the differences between all 3 readings from each subject. Coefficients of repeatability and reproducibility were computed.Results: Mean CCT as measured by each instrument were: 518.53 ± 34.96 µm (range 417.33–592.67) and 516.94 ± 33.60 µm (range 431.67–582.67) for sessions 1 and 2 respectively, with the NCSM; 546.69 ± 36.62 µm (range 457.33–617.00) and 549.78 ± 35.26 µm (range 454.00–618.67) for sessions 1 and 2 respectively, with the USP. The ultrasound CCT measurements were consistently higher than those obtained with the NCSM in both sessions 28.17 ± 19.20 µm (mean ± SD, session 1) and 32.81 ± 14.04 (mean ± SD, session 2). The repeatability coefficient for the NCSM was better in both sessions than those for USP (±10 µm vs ± 12 µm in session 1 and ±8 µm vs ±10 µm in session 2). The reproducibility coefficient with the NCSM was half that with the USP (±21 µm vs ±41 µm).Conclusion: The SP-3000P NCSM is a more precise and reproducible instrument for measurement of CCT than the USP, but both instruments are reliable, useful instruments for measuring CCT.Keywords: cornea, Topcon SP-3000P, ultrasound pachymetry, repeatability coefficient, reproducibility co

Kelechi C Ogbuehi, John C Chijuka, Uchechukwu L Osuagwu Department of Optometry & Vision Science, College of Applied Medical Sciences, King Saud University, Riyadh, Kingdom of Saudi ArabiaBackground: The purpose of this study was to evaluate the precision of intraocular pressure measurements obtained by PT100 noncontact tonometry in a handheld and slit lamp-mounted position in comparison with that of Goldmann applanation tonometry in healthy young adults.Methods: Sixty eyes from 60 subjects (30 men and 30 women) aged 22 ± 1 (range 20–24) years participated in this study. Triplicate intraocular pressure measurement of a randomly selected eye was obtained by a noncontact tonometer in a handheld and slit lamp-mounted position in a randomized order, with the Goldmann applanation tonometer always performed last. A second measurement session was carried out after one week to assess repeatability.Results: The mean ± standard deviation of intraocular pressure readings in the first and second session, respectively, with the three techniques were: handheld position, 14.52 ± 3.28 mmHg and 15.26 ± 2.11 mmHg; slit lamp-mounted position, 14.01 ± 2.80 mmHg and 15.16 ± 2.34 mmHg; and Goldmann applanation tonometer, 14.86 ± 3.26 mmHg and 15.16 ± 2.42 mmHg. There were no significant differences (P > 0.05) between the techniques in the intraocular pressure measurements returned (Goldmann applanation tonometer vs handheld and Goldmann applanation tonometer vs slit lamp-mounted). The Goldmann applanation tonometer measured intraocular pressure 0.34 mmHg higher than handheld and 0.85 mmHg higher than slit lamp-mounted in session 1, and in session 2 Goldmann applanation tonometer intraocular pressure measurement was the same as with the slit lamp-mounted method but lower than with the handheld method by 0.11 mmHg. In PT100 handheld vs slit lamp-mounted comparisons, there were n