Improved retinal function after trabeculectomy in glaucoma patients

Evaluation of changes in retinal light sensitivity thresholds in the early postoperative days after trabeculectomy using microperimetry

PURPOSE

To investigate early postoperative changes in retinal light sensitivity at the foveal and paramacular points in open angle glaucoma patients.

STUDY DESIGN

Retrospective cohort study.

METHODS

Twenty-four eyes undergoing trabeculectomy were analyzed. Retinal light sensitivity thresholds were measured using microperimetry both before and 7 days after surgery. Linear regression analysis identified factors affecting postoperative sensitivity changes. We also evaluated the correlation between changes in the threshold of retinal light sensitivity at the foveal and paramacular points.

RESULTS

Intraocular pressure significantly decreased postoperatively. The mean threshold values of retinal light sensitivity following surgery showed no statistically significant changes compared with preoperative values across all eyes. Specifically, the mean threshold values increased in 4 eyes, decreased in 2, and remained stable in 18. Upon analyzing each examination point, 71.8% eyes exhibited stability, 12.8% showed a decrease of less than -6 dB, and 15.4% demonstrated an improvement of more than +6 dB in threshold values of retinal light sensitivity post-surgery. Changes in retinal light sensitivity at most paramacular points were found to be independent of those at the fovea. Excessive IOP reduction was identified as a significant risk factor for central visual field impairment.

CONCLUSIONS

Localized changes in retinal light sensitivity thresholds can vary in the early postoperative period following trabeculectomy, highlighting the need to monitor localized retinal function to better understand its impact on visual outcomes.

Effect of trabeculectomy on the rate of progression of visual field damage

OBJECTIVES

This study quantifies the effect of trabeculectomy on the rate of progression (RoP) of visual field (VF) damage utilising pre- and post-operative visual function as the outcome instead of surrogate outcomes of success.

METHODS

Clinical and VF data from 199 sequential patients who underwent trabeculectomy between 2015 and 2016 were extracted from the network of sites of Moorfields Eye Hospital NHS Foundation Trust. Of these, we analysed 80 eyes of 74 patients who met our inclusion criteria of at least three reliable VFs before and after surgery (false positive rate <15%). The change in mean RoP (dB/year) was tested using point-wise sensitivity values through a mixed effect model with random effects on both intercepts and slopes. A broken-stick regression of sensitivity over time, with a breakpoint at the day of surgery, modelled the individual change in RoP.

RESULTS

We analysed 10 [9,12] VFs per subject (Median [Interquartile Range]). At surgery, the age was 67 [57, 72] years, mean deviation was -10.84 [-14.7, -5.6] dB and the IOP was 18 [15, 20] mmHg. One year after surgery, the IOP was 10 [8,13] mmHg (p = 0.002). Mean RoP before surgery was -0.94 [-1.20, -0.69] dB/year (Mean [95% credible intervals]) and it was slowed down by 0.62 [0.26, 0.97] dB/year (p < 0.001) after surgery.

CONCLUSIONS

Trabeculectomy leads to a significant reduction in the RoP of VF loss postoperatively.

Short-Term Changes in the Photopic Negative Response Following Intraocular Pressure Lowering in Glaucoma

Purpose

To evaluate the short-term changes in inner retinal function using the photopic negative response (PhNR) after intraocular pressure (IOP) reduction in glaucoma.

Methods

Forty-seven participants with glaucoma who were commencing a new or additional IOP-lowering therapy (treatment group) and 39 participants with stable glaucoma (control group) were recruited. IOP, visual field, retinal nerve fiber layer thickness, and electroretinograms (ERGs) were recorded at baseline and at a follow-up visit (3 ± 2 months). An optimized protocol developed for a portable ERG device was used to record the PhNR. The PhNR saturated amplitude (V_max), V_max ratio, semi-saturation constant (K), and slope of the Naka–Rushton function were analyzed.

Results

A significant percentage reduction in IOP was observed in the treatment group (28 ± 3%) compared to the control group (2 ± 3%; P < 0.0001). For PhNR V_max, there was no significant interaction (F_1,83 = 2.099, P = 0.15), but there was a significant difference between the two time points (F_1,83 = 5.689, P = 0.019). Post hoc analysis showed a significant difference between baseline and 3 months in the treatment group (mean difference, 1.23 µV; 95% confidence interval [CI], 0.24–2.22) but not in the control group (0.30 µV; 95% CI, 0.78–1.38). K and slope were not significantly different in either group. Improvement beyond test–retest variability was seen in 17% of participants in the treatment group compared to 3% in the control group (P = 0.007, χ² test).

Conclusions

The optimized protocol for measuring the PhNR detected short-term improvements in a proportion of participants following IOP reduction, although the majority showed no change.

The effect of trabeculectomy on serum brain-derived neurotrophic factor levels in primary open-angle glaucoma

PURPOSE

We aimed to investigate the effect of trabeculectomy on serum brain-derived neurotrophic factor (BDNF) levels. Our secondary goal was to compare serum and aqueous humor (AH) BDNF levels in primary open-angle glaucoma (POAG) and control subjects.

METHODS

This prospective, cross-sectional study consists of 20 eyes of with advanced-stage POAG who had trabeculectomy and 19 eyes of age- and sex-matched control healthy subjects who had cataract surgery. Serum and AH samples were obtained preoperatively in trabeculectomy group and control subjects. Serum samples were obtained at the third postoperative month in both groups.

RESULTS

The aqueous humor and serum levels of BDNF at the surgery day were found to be strongly positive correlated (r = 0.868; p < 0.001). Serum and AH BDNF levels of POAG cases were significantly lower than control subjects at the surgery day (respectively p = 0.038, p = 0.011). In POAG cases, serum BDNF levels significantly increased at the third month after trabeculectomy while there was not a significant difference in control subjects with cataract surgery (p < 0.001; p = 0.717 respectively).

CONCLUSION

Trabeculectomy was found to have a positive effect on serum BDNF levels in POAG cases.

Optical coherence tomography angiography: A comprehensive review of current methods and clinical applications

OCT has revolutionized the practice of ophthalmology over the past 10-20 years. Advances in OCT technology have allowed for the creation of novel OCT-based methods. OCT-Angiography (OCTA) is one such method that has rapidly gained clinical acceptance since it was approved by the FDA in late 2016. OCTA images are based on the variable backscattering of light from the vascular and neurosensory tissue in the retina. Since the intensity and phase of backscattered light from retinal tissue varies based on the intrinsic movement of the tissue (e.g. red blood cells are moving, but neurosensory tissue is static), OCTA images are essentially motion-contrast images. This motion-contrast imaging provides reliable, high resolution, and non-invasive images of the retinal vasculature in an efficient manner. In many cases, these images are approaching histology level resolution. This unprecedented resolution coupled with the simple, fast and non-invasive imaging platform have allowed a host of basic and clinical research applications. OCTA demonstrates many important clinical findings including areas of macular telangiectasia, impaired perfusion, microaneurysms, capillary remodeling, some types of intraretinal fluid, and neovascularization among many others. More importantly, OCTA provides depth-resolved information that has never before been available. Correspondingly, OCTA has been used to evaluate a spectrum of retinal vascular diseases including diabetic retinopathy (DR), retinal venous occlusion (RVO), uveitis, retinal arterial occlusion, and age-related macular degeneration among others. In this review, we will discuss the methods used to create OCTA images, the practical applications of OCTA in light of invasive dye-imaging studies (e.g. fluorescein angiography) and review clinical studies demonstrating the utility of OCTA for research and clinical practice.

Short-Term Moderately Elevated Intraocular Pressure Is Associated With Elevated Scotopic Electroretinogram Responses

Purpose

Moderately elevated intraocular pressure (IOP) is a risk factor for open-angle glaucoma. Some patients suffer glaucoma despite clinically measured normal IOPs. Fluctuations in IOP may have a significant role since IOPs are higher during sleep and inversion activities. Controlled transient elevations of IOPs in rats over time lead to optic nerve structural changes that are similar to the early changes observed in constant chronic models of glaucoma. Because early intervention decreases glaucoma progression, this study was done to determine if early physiological changes to the retina could be detected with noninvasive electrophysiological and optical imaging tests during moderately elevated IOP.

Methods

Intraocular pressures were raised to moderately high levels (35 mm Hg) in one eye of Sprague-Dawley rats while the other (control) eye was untreated. One group of rats underwent scotopic threshold response (STR) and electroretinogram (ERG) testing, while another 3 groups underwent optical coherence tomography (OCT) imaging, Western blot, or histologic evaluation.

Results

The amplitudes of the STR and ERG responses in eyes with moderately elevated IOPs were enhanced compared to the values before IOP elevation, and compared to untreated contralateral eyes. Structural changes to the optic nerve also occurred during IOP elevation.

Conclusions

Although ischemic IOP elevations are well-known to globally reduce components of the scotopic ERG, acute elevation in rats to levels often observed in untreated glaucoma patients caused an increase in these parameters. Further exploration of these phenomena may be helpful in better understanding the mechanisms mediating early retinal changes during fluctuating or chronically elevated IOP.

Reversible structural and functional changes after intraocular pressure reduction in patients with glaucoma

PURPOSE

The aim of this study was to evaluate structural and functional improvement following intraocular pressure (IOP) reduction in patients with glaucoma using Spectral Domain Optical Coherence Tomography (SD-OCT), Visual Field (VF) testing, and Visual Evoked Potentials (VEP).

METHODS

A total of 76 eyes from 61 patients underwent SD-OCT, VF and VEP testing. Sixty-two eyes were put in either an acutely high (group 1, IOP > 32 mmHg) or mildly high (group 2, IOP between 22 and 31 mmHg) IOP group and underwent a pressure-lowering intervention. Fourteen eyes with stable glaucoma were controls (group 3, IOP < 22 mmHg). SD-OCT, VF and VEP testing were subsequently performed on all patients at three follow-up visits. Results from these follow-up periods were analyzed for signs of functional and structural improvement.

RESULTS

Both group 1 and group 2 patients demonstrated significant decrease in the average cup to disc ratio (p < 0.05) following the intervention. Post-interventional reduction of cup volume was also significant for group 2 patients (p < 0.05). RNFL thickness changes were insignificant. Qualitative grading of VFs by two observers showed improvement in group 1 patients' VFs (p = 0.021). VEP measurements were mostly insignificant, with the exception of High Contrast Latency (LHC) deteriorating for group 2 patients in the first follow-up visit (p = 0.025).

CONCLUSIONS

This study provides evidence for structural disc cupping reversal following IOP lowering interventions. These changes were not related to the amount of pressure lowering. While there was evidence of functional improvement as measured by VF testing, VEP was unable to detect any reversible changes.

A control experiment for studies that show improved visual sensitivity with intraocular pressure lowering in glaucoma

PURPOSE

Contrast sensitivity sometimes increases in patients with open-angle glaucoma when intraocular pressure (IOP) is decreased. Although often interpreted as demonstrating reversible glaucoma-induced dysfunction, this result, if true, could simply reflect a general relationship between sensitivity and IOP in visual mechanisms unaffected by glaucoma. To investigate this relationship, we test the hypothesis that reducing IOP in eyes without glaucoma (ocular hypertension) does not increase perimetric contrast sensitivity.

DESIGN

Comparative case series.

PARTICIPANTS

A total of 692 participants drawn from the Ocular Hypertension Treatment Study (OHTS) (22 clinical centers).

METHODS

Commercially available topical ocular hypotensive medications.

MAIN OUTCOME MEASURES

Post hoc analysis of IOP and perimetric contrast sensitivity (mean deviation [MD] and pattern standard deviation [PSD]) both at baseline (0 months, immediately before ocular antihypertensive therapy) and at 6-month review. An additional 618 control eyes from OHTS that did not receive treatment were examined over the same period. Data from the second phase of OHTS also were examined, and control eyes then received treatment.

RESULTS

Treated eyes had a decrease in IOP at 6 months (5.1 mmHg, P<0.001) but no significant change in MD (0.04 decibels [dB], P = 0.59) or PSD (0.03 dB, P = 0.19), relative to controls. A similar decrease in IOP was found for eyes that began treatment in the second phase of OHTS, but no significant change in MD or PSD.

CONCLUSIONS

Despite using a large sample size, we found no relationship between perimetric contrast sensitivity and IOP reduction in ocular hypertension, which suggests that previous sensitivity changes seen in patients with glaucoma, if true, are indicative of reversible glaucoma-induced dysfunction rather than a general relationship between sensitivity and IOP in visual mechanisms unaffected by glaucoma.

Visual recovery in a patient with total hyphema, neovascular glaucoma, long-standing retinal detachment and no light perception vision: a case report

Introduction

We report the case of a patient with total hyphema, neovascular glaucoma, long-standing retinal detachment and no light perception vision, who regained counting fingers vision with complete regression of neovascularization following anterior chamber washout, intravitreal bevacizumab, pars plana vitrectomy, and silicone oil placement. This represents a rare case in which a patient with no light perception vision was able to regain functional vision.

Case presentation

A 63-year-old Caucasian man with a 55-year history of long-standing retinal detachment after trauma presented to our facility with pain and redness, a total hyphema, no light perception vision and an intraocular pressure of 60 mmHg (right eye). He had a history of diabetes mellitus and coronary artery disease. Following anterior chamber washout, he was found to have neovascular glaucoma, for which intravitreal bevacizumab was administered. After washout and intraocular pressure control, his visual acuity improved to light perception. He subsequently underwent vitrectomy, membrane peeling, endolaser and silicone oil placement to reattach his retina, and then a second retinal reattachment procedure. Following these procedures, he had visual recovery to counting fingers vision in his right eye at five metres, complete regression of neovascularization, and intraocular pressure of 10 to 12 mmHg on one antiglaucoma medication.

Conclusion

Functional vision can be regained despite long-standing retinal detachment.

The impact of intraocular pressure reduction on retinal ganglion cell function measured using pattern electroretinogram in eyes receiving latanoprost 0.005% versus placebo

PURPOSE

To evaluate the impact of intraocular (IOP) reduction on retinal ganglion cell (RGC) function measured using pattern electroretinogram optimized for glaucoma (PERGLA) in glaucoma suspect and glaucomatous eyes receiving latanoprost 0.005% versus placebo.

METHODS

This was a prospective, placebo-controlled, double masked, cross-over clinical trial. One randomly selected eye of each subject meeting eligibility criteria was enrolled. At each visit, subjects underwent five diurnal measurements between 8:00 am and 4:00 pm consisting of Goldmann IOP, and PERGLA measurements. A baseline examination was performed following a 4-week washout period, and repeat examination after randomly receiving latanoprost or placebo for 4-weeks. Subjects were then crossed over to receive the alternative therapy for 4 weeks following a second washout period, and underwent repeat examination. Linear mixed-effect models were used for the analysis.

RESULTS

Sixty-eight eyes (35 glaucoma, 33 glaucoma suspect) of 68 patients (mean age 67.4 ± 10.6 years) were enrolled. The mean IOP (mmHg) after latanoprost 0.005% therapy (14.9 ± 3.8) was significantly lower than baseline (18.8 ± 4.7, p<0.001) or placebo (18.0 ± 4.3), with a mean reduction of -20 ± 13%. Mean PERGLA amplitude (μV) and phase (π-radian) using latanoprost (0.49 ± 0.22 and 1.71 ± 0.22, respectively) were similar (p > 0.05) to baseline (0.49 ± 0.24 and 1.69 ± 0.19) and placebo (0.50 ± 0.24 and 1.72 ± 0.23). No significant (p > 0.05) diurnal variation in PERGLA amplitude was observed at baseline, or using latanoprost or placebo. Treatment with latanoprost, time of day, and IOP were not significantly (p > 0.05) associated with PERGLA amplitude or phase.

CONCLUSION

Twenty percent IOP reduction using latanoprost monotherapy is not associated with improvement in RGC function measured with PERGLA.

Reversal of retinal ganglion cell dysfunction after surgical reduction of intraocular pressure

PURPOSE

The pattern electroretinogram optimized for glaucoma screening (PERGLA) is a noninvasive method of objectively measuring retinal ganglion cell (RGC) function. This study was undertaken to quantify the RGC response to intraocular pressure (IOP) reduction after glaucoma surgery.

DESIGN

Prospective cohort study.

PARTICIPANTS

Forty-seven eyes of 47 patients with uncontrolled IOP or progressive glaucomatous optic neuropathy receiving maximal medical therapy requiring trabeculectomy or aqueous drainage device implantation who met eligibility criteria.

METHODS

Eyes with visual acuity less than 20/30, corneal or retinal pathologic features, or unreliable standard automated perimetry (SAP) results were excluded. All patients underwent complete ocular examination, arterial blood pressure, SAP, and PERGLA at 2 sessions before surgery and at 3 months after surgery. Mean ocular perfusion pressure (MOPP) was calculated. Each measure of PERGLA amplitude and phase was an average of 600 artifact-free signal registrations.

MAIN OUTCOME MEASURES

Intraocular pressure and PERGLA amplitude and phase.

RESULTS

Forty-seven eyes of 47 patients (mean age ± standard deviation [SD], 69.9 ± 11.3 years) were enrolled. Thirty-four eyes (72%) underwent trabeculectomy with antifibrosis therapy; 13 eyes (28%) underwent glaucoma drainage implant surgery. Mean ± SD postoperative IOP (10.4 ± 4.6 mmHg) was significantly (P< 0.001) reduced compared with that before surgery (19.7 ± 8.6 mmHg). Mean ± SD postoperative PERGLA amplitude (0.46 ± 0.22 μV) was significantly (P = 0.001) increased compared with preoperative PERGLA amplitude (0.37 ± 0.18 μV). Mean ± SD postoperative PERGLA phase (1.72 ± 0.20 π-radian) was significantly (P = 0.01) reduced compared with preoperative PERGLA phase (1.81 ± 0.22 π-radian). Mean ± SD postoperative MOPP (53.1 ± 6.4 mmHg) was significantly (P < 0.001) increased compared with mean ± SD preoperative MOPP (45.8 ± 10.1 mmHg). No correlation (P > 0.05) was identified between change in PERGLA amplitude and change in IOP or MOPP.

CONCLUSIONS

Reversal of RGC dysfunction occurs after surgical reduction of IOP and may be quantified using PERGLA.