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Trabeculectomy is the most common surgical procedure for the management of glaucoma, which may significantly influence ocular biometry. Axial length and anterior chamber depth tend to decrease, while crystalline lens and choroidal thickness increase post-operatively. An increase in with-the-rule astigmatism is also observed after the procedure. Such biometric changes affect intraocular lens power calculation even years after the procedure. Non-contact biometric methods and postponing cataract surgery after trabeculectomy could reduce calculation errors associated with surgically induced alterations in ocular biometrics.

PURPOSE To compare biometric changes measured with contact and noncontact methods after mitomycin-C-augmented trabeculectomy. METHODS In this prospective study, 31 eyes from 31 glaucoma patients scheduled for primary trabeculectomy were enrolled. Biometric parameters including axial length (AL), anterior chamber depth (ACD), and lens thickness (LT) were measured using contact ultrasound biometry (UD-6000 Ultrasonic A/B scanner biometer; Tomey Corporation, Nagoya, Japan) and a noncontact optical biometry device (Lenstar; Haag-Streit AG, Koeniz, Switzerland). Measurements were taken the day before trabeculectomy and then compared with measurements obtained 3 and 6 months after surgery. RESULTS The AL and ACD were significantly decreased at 3 and 6 months compared with baseline values taken with each biometry method. There was a significant increase in LT measured by the Lenstar device at the 3- and 6-month follow-up. At both the 3- and 6-month follow-up, the mean AL measurement reduction with the Lenstar device was significantly lower than that of the A-scan ultrasound measurements. The mean ACD changes between the two devices were not significantly different. CONCLUSIONS There is a small but significant decrease in the AL and ACD after trabeculectomy as measured with both the contact and noncontact methods. The amount of AL reduction measured is significantly smaller using the noncontact method, making it the preferable method for intraocular lens power calculation for patients who need cataract surgery combined with or after trabeculectomy. The LT measured by the Lenstar device increased significantly after the operation, which can be an early sign of the progression of cataractous changes after trabeculectomy.

This review article aimed to evaluate ocular biometric changes after trabeculectomy. The PubMed database was searched using the keywords "axial length" (AL), "anterior chamber depth" (ACD), "corneal astigmatism," "corneal topography" and "trabeculectomy." The extracted studies were categorized based on the evaluated parameters and the biometry method (contact and non-contact). Comparable studies with respect to their sample size were combined for statistical analysis. Twenty-five studies including 690 individuals which met the inclusion criteria were selected. After trabeculectomy, a significant and persistent AL reduction, with a range of 0.1-0.19 and 0.1-0.9 mm measured with contact and non-contact methods, respectively, was observed. With respect to topographic changes, 0.38-1.4 diopters (D) with-the-rule (WTR) astigmatism was induced postoperatively. All studies revealed ACD reduction immediately after surgery, which gradually deepened and approximated its preoperative levels on day 14. ACD reduction was not significant after that period in the majority of cases. In conclusion, changes in ACD is of small amount and of short period, thus it can be ignored; however, reported changes in AL and keratometry are of sufficient magnitude and can affect the refractive prediction of combined cataract surgery and trabeculectomy.

To compare surgical sequences of combined intracorneal ring segment (ICRS) implantation and corneal collagen cross-linking (CXL) in keratoconus and corneal ectasia in terms of visual, refractive, and keratometric outcomes.A comprehensive electronic search (in PubMed, Web of Science, Scopus, Embase, and Cochrane Library) was conducted in accordance with the PRISMA statement to find articles on combined ICRS implantation and CXL in keratoconus and corneal ectasia. The search period was from the inception of the database up to April 2017. Eligible articles were categorized into 3 surgical sequences (same day, ICRS first, and CXL first) and assessed qualitatively. Articles with 12 months of follow-up data after combined surgery were included in the meta-analysis.The initial search identified 120 related articles, of which 17 were included in the review after screening. The quality assessment showed that visual, refractive, and keratometric improvement was observed in all studies in all 3 groups of combined surgery. Meta-analysis on 6 studies that reported 12-month follow-up outcomes showed no significant differences between the 3 groups regarding uncorrected and best-corrected visual acuity and cylindrical refractive error. However, results with simultaneous surgery were superior to the CXL-first technique in terms of spherical refractive errors and flat-K (P = 0.011 and P = 0.0001, respectively) and to both CXL first and ICRS first in terms of steep-K (P = 0.002 and P = 0.007, respectively).Simultaneous ICRS implantation and CXL may provide better outcomes than staged techniques for improving the corneal shape.

Purpose To evaluate biometric changes after mitomycin C augmented trabeculectomy and their effect on intraocular lens (IOL) power calculation using different formulas. Methods In this prospective, interventional case series study, 34 eyes of 31 phakic glaucoma patients who were scheduled for primary trabeculectomy were enrolled. Using a noncontact biometry device (Lenstar, Haag-Streit AG, Koeniz, Switzerland), axial length (AL), mean corneal power, and IOL power were calculated with the Hoffer Q, Holladay, and SRK/T formulas 1 day before surgery and compared to those obtained 3 and 6 months after the operation. Bland-Altman plot was used to determine agreement between preoperative and postoperative IOL power values. Results The AL was significantly decreased at month 3 (-0.14 ± 0.13 mm) and month 6 (-0.14 ± 0.15 mm) as compared to baseline values (both p values Conclusions Despite significant changes in AL and corneal power after trabeculectomy, IOL power calculation remains unchanged; therefore adjustment of IOL power calculation after trabeculectomy seems unnecessary.