Increased Retinal Layer Thickness. Would it Help to Preserve Vision in Glaucoma?
Mr. Karthik Kumar, Dr. Donamol Cyriac, Dr. Prabhat Nangia, Dr. Sarang Lambat and Dr. Vinay Nangia
Suraj Eye Institute, 559 New Colony, Nagpur
Case Description
A male, 60 year old presented to us with complaints of blurring of vision in both eyes since 6 months which was gradual and worsening. There was no past ocular or medical history. His best corrected visual acuity was 6/6, N6 in the right eye with +2.00DS/ +0.50DC x 5 and 6/6, N6 in the left eye with +1.50DS/+1.50DC x 10. Anterior segment examination was normal in both eyes. Intraocular pressure recorded by Goldmann applanation tonometer was 20mmHg in both eyes. Fundus examination of both eyes showed 0.6 vertical cup disc ratio. On digital biometry axial length was 22.63mm in right eye and 22.51mm in left eye. Lens thickness was right eye 4.63mm and left eye 4.66mm. Aqueous depth was RE 2.58mm and LE 2.43mm. Anterior chamber depth was 3.10mm in right eye and 2.96mm in the left eye. Gonioscopy showed open angles both eyes. Corneal curvatures in the right eye were: 44.80D x 14º and 44.73D x 104º and in the left eye it was 44.75D x 4º and 44.43D x 94º.
Figure 2 – Colour fundus photograph of left eye (B) shows Vertical cup disc ratio of 0.6 and prominent retinal nerve fiber layer (yellow arrows).
Figure 4 – SD-OCT circumpapillary RNFL scan of left eye (B) shows increased thickness of retinal nerve fibre in all the quadrants and double peak superiorly (blue arrows) and inferiorly (yellow arrows).
Figure 6 – SD-OCT posterior pole ganglion cell layer heat map (A) and deviation map (B) of left eye shows increased ganglion cell layer thickness (red arrows).
Figure 8 – SD-OCT posterior pole inner plexiform layer heat map(A) and deviation map(B) shows thickening of inner plexiform layer in all quadrants (red arrow).
Discussion
Our patient had normal ocular parameters in all respects. He caught our attention, because at the age of 60 years he presented with very healthy-looking retinal nerve fibre layer clinically (Fig 1 and 2 red arrows). The RNFL scans (Fig. 3 and 4) also showed healthy RNFL and there were two peaks superiorly and inferiorly in both eyes (Fig. 3, b and c blue and yellow arrows and Fig. 4, b and c blue and yellow arrows).
The patient also had a very healthy ganglion cell layer in RE (Figure 5 and 6, a and b, red arrows) the percentile values were more than 90% in all segments and 95% globally (Fig 5 and 6, c, red arrows). This is rather unusual and seen only rarely. It is also interesting to note that the Inner plexiform layer was also thickened in all quadrants (Fig. 7 and 8 a and b, red arrows) The global percentile values of IPL were more than 99% (Fig. 7 and 8 c, red arrows). This is rare and unusual. It is attractive to consider if our patient may be less susceptible to glaucomatous damage, if it were to occur. Would glaucoma damage take longer to manifest. Would the patient therefore be much safer? All ocular measurements were taken, and they were within normal limits. The OCT scans did not show any abnormality. The explanation for this phenomenon is not clear. One may hypothesise that perhaps retinal layer thickness may be influenced through genetic factors. This leaves us with a very interesting discussion whether there is a possibility, that one may be able to alter the susceptibility of patients to glaucomatous damage.
ReadWise
- Mwanza JC, Durbin MK, Budenz DL, Girkin CA, Leung CK, Liebmann JM, Peace JH, Werner JS, Wollstein G, Cirrus OCT Normative Database Study Group. Profile and predictors of normal ganglion cell–inner plexiform layer thickness measured with frequency-domain optical coherence tomography. Investigative ophthalmology & visual science. 2011 Oct 1;52(11):7872-9. doi: 10.1167/iovs.11-7896.
- Koh VT, Tham YC, Cheung CY, Wong WL, Baskaran M, Saw SM, Wong TY, Aung T. Determinants of ganglion cell–inner plexiform layer thickness measured by high-definition optical coherence tomography. Investigative ophthalmology & visual science. 2012 Aug 1;53(9):5853-9. https://doi.org/10.1167/iovs.12-10414
Correspondence
Dr Vinay Nangia
MS, FRCS, FRCOphth
Director
Suraj Eye Institute
Nagpur
Email –education@surajeye.org