Macular thickness changes using Spectral Domain Optical Coherence Tomography after glaucoma surgery

Abstract

 

Purpose

 

Reversal of disc cupping following glaucoma surgery is known to occur for decades, however there is limited data on its impact on the macula. The purpose of this study was to assess macular thickness changes following glaucoma surgery using macular Spectral Domain Optical Coherence Tomography (SD-OCT).

 

Methods

 

A retrospective chart review of patients who underwent glaucoma surgery between January 2012 and February 2013 was conducted. Patients were included if they had an SD-OCT “Asymmetry Analysis” scan (Spectralis, Heidelberg Engineering, Carlsbad, CA, USA) within 1 year prior to surgery and at least one scan following surgery. Patients with maculopathy were excluded. Outcome measures were macular thickness and IOP.

 

Results

 

The study consisted of twelve patients. Postoperative scans were conducted after an average of 10.8 (+5.3) months. Nine out of 12 patients (75%) showed increases in macular thickness. The mean macular thickness increased from 263μm to 272μm (p=0.079) following a significant reduction in IOP (p<0.001). There was a significant increase in macular thickness in the superior hemisphere (p=0.043). Figure 1 shows the SD-OCT scans of a patient with a substantial increase in macular thickness following surgery.

 

Conclusions

 

This pilot study found a significant increase in mean superior hemifield macular thickness following glaucoma surgery.  

 

Figure 1. Macular spectral domain-optical coherence tomography scans of a 79 year-old patient with primary open-angle glaucoma status-post cataract and trabeculectomy surgery in the left eye. Macular thickness was measured along 61 lines (30° x 25° optical coherence tomography volume scans) in the central 20° of the posterior pole. A color-coded retinal thickness map for an 8x8 millimeter grid is demonstrated. The grid is centered on the foveal pit and aligned with the optic nerve head. This grid is divided into small 3° x 3° squares, representing approximately one square millimeter of the retina. Mean retinal thickness of each square is shown. (A) Nine months preoperatively, total macular thickness was 240μm. (b) Fourteen months postoperatively, total macular thickness increased to 265μm. Additionally, the mean retinal thickness increased for all squares except for one that lacked data.