Dr. Ravi Daberao, Dr. Prerna Agrawal, Dr. Sarang Lambat, Dr. Prabhat Nangia,
Dr. Vinay Nangia
Case description
A 45-year-old male presented to our clinic for a glaucoma evaluation. His best-corrected visual acuity was 6/6 in both eyes. During the anterior segment examination, conjunctival congestion was observed in both eyes while the rest of the examination was normal. The intraocular pressure in both eyes was 20 mmHg while using timolol 0.50%. Gonioscopy revealed open angles in both eyes. The axial length of his right eye was measured at 22.76 mm, and the left eye was 22.59 mm. Additionally, the central corneal thickness in the right eye was 526 microns, and in the left eye, it was 527 microns. To manage his glaucoma, he was started on bimatoprost 0.01% eyedrops along with timolol 0.50% in both eyes.
The patient underwent a bent ab interno goniectomy on 17/01/2023 in the left eye. During a follow-up examination after three weeks, the intraocular pressure was measured at 20 mmHg in the right eye and 14 mmHg while using a combination of timolol 0.50% and bimatoprost 0.01% in both eyes.
Fig. 1 The colour fundus photograph of the right eye showed a cup-to-disc ratio of 0.7:1 along with inferior rim thinning (shown by the red arrow).
Fig. 2 The colour fundus photograph of the left eye showed a cup-to-disc ratio of 0.75:1 accompanied by an inferior rim notch (as marked by the red arrow). The yellow arrow denotes the presence of a broad wedge-shaped RNFL defect.
Fig. 3: The OCT image of the right eye depicts a normal appearance of the circumpapillary retinal nerve fibre layer (RNFL) (indicated by the yellow arrow in Fig. 3b and the black arrow in Fig. 3d).
Fig. 4: The OCT image of the left eye reveals significant thinning of the circumpapillary retinal nerve fibre layer (RNFL) in the inferotemporal segments (indicated by the white arrow in Fig. 4b and black arrow in Fig. 4d.)
Fig.5 Right eye posterior pole deviation map showed a small area of early ganglion cell layer thinning in the area of the raphe, suggesting an early development of an evolving temporal step of GCL loss. (Fig.5 A, yellow arrow) (Fig 5 B, red arrow).
Fig. 6: The deviation map of the left eye posterior pole demonstrates thinning of the ganglion cell layer in the inferior and inferotemporal sectors (indicated by the yellow arrow in Fig. 6A and white arrow in Fig. 6B). The classification of the macular ganglion cell layer displays thinning of the ganglion cell layer in the inferior and inferotemporal sectors at less than the 1st percentile (indicated by the blue arrow in Fig. 6D).
Fig. 7: The right eye’s 30-degree standard visual field test reveals an early visual field defect (red arrow) in the nasal region.
Fig. 8: The right eye’s 12-degree standard visual field test (M pattern) shows normal results
Fig. 9: The left eye’s 30-degree standard visual field test indicates a superior field defect.
Fig. 10: The left eye’s 12-degree standard visual field test (M pattern) reveals a superior field defect corresponding to the inferior ganglion cell layer thinning observed on optical coherence tomography.
| Discussion The patient presented with primary open-angle glaucoma and exhibited significant cupping in both eyes. Retinal nerve fiber layer (RNFL) imaging of the right eye showed no apparent loss, which can be a limitation as early RNFL loss may go undetected when values fall within the 95th percentile and are considered normal. However, the appearance of the optic disc in the right eye was highly suspicious of glaucoma in a patient with primary open-angle glaucoma, where the left eye optic disc exhibited obvious glaucomatous cupping. While the RNFL of the right eye was within normal limits, the ganglion cell layer heat map and deviation map revealed the loss of ganglion cell layer (GCL) in the area of the raphe, suggesting an early development of a temporal GCL defect. Furthermore, the 30-degree visual field showed an early nasal field loss corresponding to the temporal area of GCL loss. In the left eye, significant inferotemporal RNFL loss and GCL loss inferior to the fovea extending temporally were observed, corresponding to visual field loss. This case is of particular interest due to the appearance of the optic disc in the right eye, without any apparent RNFL defect either clinically or on OCT, but with early ganglion cell loss and early nasal field defect loss. This indicates the onset of early glaucoma. In the left eye, there is a significant loss of inferior RNFL and GCL, and the central visual field loss almost reaches up to the fovea. Consequently, there is a case for setting a low target pressure for the right eye, and greater care is necessary to avoid missing early signs in patients. Multimodal imaging is now integral to glaucoma diagnosis and follow-up, with the goal of preserving as many ganglion cells as possible in glaucoma patients. |
ReadWise
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- VKS, Kalyani; Bharucha, Khurshed M; Goyal, Nikhil1,; Deshpande, Madan M. Comparison of diagnostic ability of standard automated perimetry, short wavelength automated perimetry, retinal nerve fiber layer thickness analysis and ganglion cell layer thickness analysis in early detection of glaucoma. Indian Journal of Ophthalmology 69(5):p 1108-1112, May 2021. | DOI: 10.4103/ijo.IJO_2409_20
Correspondence
Dr Vinay Nangia
MS, FRCS, FRCOphth
Director
Suraj Eye Institute
Email – education@surajeye.org