GlaucomaLearn 4 (Right eye) - Suraj Eye Institute

Vinay Nangia, Ravi Daberao

A CASE PRESENTATION:

A female 50 year of age, came for a follow up for glaucoma. Her best corrected visual acuity was 6/6 in right eye and 6/6 in left eye. Anterior segment examination was normal. Right eye intraocular pressure was 16 mmHg and left eye was 17 mmHg. She was on brimonidine tartrate (0.2%) and timolol maleate (0.50 %) combination eyedrops since 2 years. Gonioscopy showed open angles in both eyes. Her axial length in right eye was 21.89 mm and left eye 21.93 mm. Her central corneal thickness in right eye was 458 microns and left eye was 478 microns.

Figure 1A: Colour photograph of fundus of right eye showed a cup disc ratio of 0.7. Classical inferior retinal nerve fiber defect was seen (yellow arrow).The macula was normal

Figure 1B: Colour photograph of fundus of right eye under greater magnification

Figure 2: Right eye OCT circumpapillary retinal nerve fiber layer (RNFL) showed significant thinning of infero-temporal RNFL (yellow arrow) (Fig. 2b) and (black arrow) (Fig. 2d). The previous scan was performed 6 months before. Over this period of time there was no significant loss of RNFL and only very minimal loss was seen

Figure 3: Right eye posterior pole deviation map showed significant reduction in ganglion cell layer thickness (yellow arrows) (Fig.3 A and B) in inferior and inferior temporal quadrants. GCL segmental measurements in the macula showed thinning of infero-temporal, inferior sector and supero-temporal quadrants < 1 percentile (Fig.3 D). Superior sector showed GCL thinning of <5th percentile of healthy reference population (Fig.3 D). GCL global average also showed thinning <1 percentile of healthy reference population (Fig.3 D).

Figure 4: Right eye Hood’s report showed reduction in retinal nerve fiber cell layer thickness in temporal quadrant (Fig.4A white arrow) and (Fig.4B black arrow). There is a significant reduction of inferior RNFL as shown by the heat map (Fig. 4D black arrows) and the field view (Fig. 4F white arrow). There is also significant reduction of inferior macular GCL shown by the heat map (Fig. 4E red arrow) and the field view (Fig. 4G yellow arrow).

Impression: The intraocular pressure in the right eye was borderline with two anti-glaucoma medications. Fundus showed a cup disc ratio of 0.70, with a classical wedge-shaped defect of RNFL inferiorly. On OCT, the patient has significant retinal nerve fiber layer and ganglion cell layer thinning in the right eye. Fig 2d shows that in the inferotemporal segment where there is significant loss already, no further deterioration was noted. In the other segments, minimal changes in RNFL thickness were seen. It may be important that the central corneal thickness was low ( 458 microns) and this may have affected the IOP measurement. In view of the significant glaucomatous damage and for better control of intraocular pressure, the patient has advised the use of prostaglandins for better control of IOP. The option of surgery was also discussed. It is important to take into consideration, that a low CCT which leads to a lower IOP measurement, may influence our decision. If the CCT was normal, the IOP may have been higher. When we add a third glaucoma medication, we would expect a certain pressure drop. However, with a lower CCT, the pressure-reducing efficacy with the third drop may be less easily manifested due to the low CCT and lower IOP measurement. This constitutes a major clinical challenge in treating patients with lower central corneal thickness

Dr. Vinay Nangia
MS, FRCS, FRCOphth
Director
Suraj Eye Institute
Email – education@surajeye.org

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