Dr. Prerna Agrawal, Dr. Sarang Lambat, Dr. Prabhat Nangia, Dr. Vinay Nangia.
Case Description
On February 10th, 2023, a 62-year-old female presented to the clinic with a complaint of reduced vision in her right eye over the past six months. Her best-corrected visual acuity was 6/24p with -5.50DS in the right eye (RE) and 6/9 with -1.50DS/ +2.00DC @ 176 in the left eye (LE). During the anterior segment examination, grade 2 nuclear sclerosis was observed in the RE, whereas early lens changes were noted in the LE. The intraocular pressure was found to be 18 mmHg in the RE and 19 mmHg in the LE, with open angles observed on gonioscopy. Fundus examination revealed a vertical cup-disc ratio of 0.8:1 with superior and inferior rim loss in both eyes. The central corneal thickness was measured as 488 µm in the RE and 491 µm in the LE, and the axial length was 24.73 mm and 24.05 mm, respectively. All other findings were within normal limits. The patient was diagnosed with primary open-angle glaucoma and age-related nuclear sclerosis.
Fig. 1 A colour photograph of the fundus of RE showed a cup disc ratio of 0.8 (white arrow). There is a generalized loss of retinal nerve fiber striation with significant loss of the neuroretinal rim.
Fig. 2 A colour photograph of the fundus of LE showed a cup disc ratio of 0.8 (white arrow). There is a generalized loss of retinal nerve fiber striation with significant loss of the neuroretinal rim.
Fig. 3 Right eye OCT circumpapillary retinal nerve fiber layer (RNFL) showed marked thinning in several sectors, including in the macular segment (Fig.3b, white arrows) (Fig.3d, black arrow).
| Fig. 4 Left eye OCT circumpapillary retinal nerve fiber layer (RNFL) showed marked thinning in superotemporal, macular and nasal sectors. (Fig.4b, white arrows) (Fig.4d, black arrows). |
Figure 5: RE posterior pole deviation map showed a generalized reduction in ganglion cell layer thickness in all sectors (yellow arrows) (Fig.5A and B). GCL thickness deviation map showed loss of ganglion cell layer in all sectors. Macular GCL classification showed outside normal limits of GCL thickness.
Fig. 6: LE posterior pole deviation map showed thinning of ganglion cell layer thickness in all sectors (yellow arrows) (Fig.6 A and B). GCL thickness deviation map showed loss of ganglion cell layer in all sectors. Macular GCL classification showed outside normal limits GCL thickness (Fig.6D)
Discussion:
The patient we examined had an increased axial length of 24.73 mm in the RE and 24.05 mm in the LE, with greater nuclear sclerosis in the RE, resulting in more myopia. We observed obliquely oval discs in both eyes, with the presence of parapapillary zones of gamma causing the superotemporal and inferotemporal vessels to draw closer together, especially in the RE. This leads to a concentration of retinal nerve fibers in the macular segment, resulting in thicker macular fibers. However, in the RE, we observed significant thinning of macular fibers (Fig.3c, 3d, black arrows), with relatively preserved superotemporal and inferotemporal nerve fibers (Fig.3d, red arrows). This is an uncommon form of glaucomatous loss that can affect central vision relatively early in the life of glaucoma. The central vision is ultimately preserved by the macular fibers. The loss of macular fibers is also associated with a loss of ganglion cells in the central macular area (Fig.5a and 5b, yellow arrows).
In the LE, we noted a nasal shift of the superotemporal and inferotemporal retinal nerve fiber layer (RNFL), along with significant thinning of the temporal macular nerve fibers. The pattern of temporal RNFL thinning in the LE is similar to what we saw in the RE. The deviation maps in Fig.5b and 6b (yellow arrow) showed a pattern of ganglion cell layer (GCL) loss that is concerning since it threatens central vision. To manage the patient’s condition, we aimed for intraocular pressure (IOP) in the low teens and started her on brimonidine, timolol, and latanoprost. We also informed her about the possibility of cataract and glaucoma surgery in the RE. Considering that the patient has a lower central corneal thickness, we kept this in mind while setting the target pressure.
This case is unusual because there is a relatively early loss of macular nerve fibers in myopia in glaucoma. In general in glaucoma, the RNFL thickness of the macular segment is relatively preserved even after significant loss of the superior and inferior RNFL has taken place. The relatively early macular loss is a possible indication that one may expect an early loss of central vision in such a patient. Therefore there is a need to reduce intraocular pressure as much as possible.
Read Wise
1. Tan, Nicholas Y.Q. Sng, Chelvin C.A. Ang, Marcus. Myopic optic disc changes and its role in glaucoma. Current Opinion in Ophthalmology 30(2):p 89-96, March 2019. | DOI: 10.1097/ICU.0000000000000548
2. Rezapour, J., Bowd, C., Dohleman, J., Belghith, A., Proudfoot, J. A., Christopher, M., Hyman, L., Jonas, J. B., Fazio, M. A., Weinreb, R. N., & Zangwill, L. M. (2021). The influence of axial myopia on optic disc characteristics of glaucoma eyes. Scientific Reports, 11. https://doi.org/10.1038/s41598-021-88406-1
QuizWise
Q.1 What is the first part of the macula affected in glaucoma?
A) Inferior
B) Superior
C) Temporal
D) Nasal
Q2) Which structural thinning is typically observed first in early-stage glaucoma?
A) Macular GCIPL
B) Parapapillary retinal nerve fiber layer
C) Both
D) None
Q. 3 Which type of glaucoma is commonly associated with myopia?
A) Pigmentary glaucoma
B) Primary open-angle glaucoma
C) Normal tension glaucoma
D) Secondary glaucoma
Q. 4 Which site of the optic nerve is identified as the main site of retinal ganglion cell Injury?
A) Lamina cribrosa
B) Bruch’s membrane opening
C) Both
D) None
Dr Vinay Nangia
MS, FRCS, FRCOphth
Director
Suraj Eye Institute
Email – education@surajeye.org