Central retinal vessel trunk exit location: An important factor while evaluating the neuroretinal rim

PURPOSE

Optic nerve head (ONH) evaluation plays a key role in differentiating normal from glaucomatous disk. Thinning of the inferior neuroretinal rim (NRR) has been noted in early glaucoma. However, NRR thickness in different quadrants appears to depend on various factors including central retinal vessel trunk exit (CRVT) position. We evaluated ocular parameters that determined the NRR thickness in the different quadrants of normal eyes.

METHODS

Retrospective review of demographic and ocular data from 773 eyes of 388 subjects with normal ONH over one year was undertaken.

RESULTS

Nearly 54% were males, and the mean age was 43.2 years. The CRVT exit was central in 50% (773). The common site for noncentral CRVT was superotemporal (ST) [37%, 141/384] followed by inferotemporal (IT) [35%, 135/384]. With noncentral CRVT, the probability that the inferior, superior, nasal and temporal (ISNT) rule was not followed was 1.42 times ( P < 0.001). The thinnest rim quadrant (TRQ) was mostly ST (69%) irrespective of CRVT location. The TRQ was IT in 40% when CRVT was noncentral and 82% with IT CRVT exit. With noncentral CRVT, round disks favored noncompliance [132 (54.1%), odds ratio (OR) 2.56] with the ISNT rule. The OR of noncompliance with the ISNT rule increases 1.89 times with inferonasal CRVT and 1.22 times with a unit increase in the axial length.

CONCLUSION

TRQ was IT in IT CRVT, and noncompliance with the ISNT rule was observed with large disks, longer axial length, and noncentral CRVT. This implies that despite the ISNT rule being violated these eyes do not have optic nerve pathology and should not be subjected to unnecessary diagnostic tests.

Consensual eye intra-ocular pressure rise following unilateral glaucoma surgery

Purpose

Consensual eye intra-ocular pressure (IOP) increase has been reported following ipsilateral glaucoma surgery. The study evaluated the need for increase in anti-glaucoma medications (AGM) ± glaucoma surgery to control the IOP in consensual eye following unilateral glaucoma surgery.

Methods

Data of 187 consecutive patients who underwent either trabeculectomy or AGV implant were collected. Index (IE) and fellow eye (FE) IOP (baseline, follow-up day 1, week 1, months 1 and 3), acetazolamide and AGM use, FE surgery, glaucoma status, and relevant ophthalmological data were collected.

Results

A significant increase from a baseline IOP of 14.4 mmHg was noted at week 1 (15.8 mmHg, p-0.005) and month 1 (15.62 mmHg, p-0.007) in FE (n-187). Among the 61 patients (33%, n-187) who needed additional intervention to reduce FE IOP, 27 (14.4%) underwent FE trabeculectomy. In the IE trabeculectomy group (n-164), significant increase in FE IOP was noted in week 1 (15.87 mmHg, p-0.014) and month 1 (15.61 mmHg, p-0.02), and in the IE AGV group (n-23) at day 1 (15.91 mmHg, p-0.06). Pre-operative acetazolamide resulted in significant increase in FE IOP at week 1 and month 1. Maximum increase in FE IOP of nearly 3.5 mm Hg was noted when IE IOP was persistently <5 mmHg at one month following surgery. Mean FE IOP remained elevated at all visits.

Conclusion

An increase in fellow eye IOP needing any additional intervention in a third and surgical intervention in nearly a sixth meant that FE IOP be strictly monitored and addressed following unilateral glaucoma surgery.