Spark ImageWise 39

A Case of  Optic Disc Pit Associated Maculopathy

Dr. Shashank Somani, Dr. Sarang Lambat, Dr. Prabhat Nangia, Dr. Vinay Nangia 
Suraj Eye Institute, 559, New Colony, Sadar, Nagpur- 440001.

Case Description
A male, 23 years of age, came with complaints of blurring of vision in right eye since 1 month. His best corrected visual acuity was 6/36, N36 in right eye and 6/6, N6 in left eye. Anterior segment examination was normal in both the eyes. Intraocular pressure recorded by Goldmann applanation tonometer was 16 mmHg in both eyes. 

Figure 1: Fundus photograph of the right eye shows a moderately large optic disc. There is a pale oval area within the cup at its temporal margin causing thinning of the temporal rim and distorting the disc margin (green Asterix). A well defined circular area (yellow arrows) which represents the edge of intra-retinal fluid can be seen in macular region. Another well defined circular area concentric with the outer area is seen which represents the presence of subretinal fluid. (Blue arrows)
Figure 2: Fundus photograph of the left eye shows vertically oval disc of small size than right eye with cup disc ratio of 0.3:1. blood vessels and macula appears normal.
Figure 3a: The optical coherence tomography line scan of right eye passing through the fovea shows loss of foveal contour with schitic changes in the outer nuclear and inner nuclear layers along with presence of sub retinal fluid (yellow arrow). There is presence of intra-retinal edema in the outer nuclear layer (green arrow).
Figure 3b:
OCT line scan passing through a different section shows outer lamellar hole (cyan arrow) which is regarded as a possible communication between intraretinal and subretinal fluid.
Figure 4: The optical coherence tomography line scan of left eye passing through macula shows normal foveal contour.

Based on the clinical and OCT findings, a diagnosis of optic disc pit maculopathy was made in the right eye and the patient was advised to undergo right eye pars plana vitrectomy with internal limiting membrane (ILM) peeling with sulphur hexafluoride (SF6) gas injection. The patient underwent surgery on 17-03-2020.

Post surgery there was gradual reduction in the sub sensory fluid over several months with improvement in the visual acuity to 6/12p, N18 at 6 months and  6/9, N12 at 2 year follow up.

Figure 5: The optical coherence tomography line scan of RE passing through macula shows reduction in intraretinal and sub sensory fluid. The progressive line scans show decrease in the fluid over a period of time which is associated with reattachment of the retinal layers.
In the infrared photographs, we can appreciate the reduction in SRF in fig 5b (green arrow) as compared to that in fig 5a (yellow arrow) which got completely resolved over a period of time and we can only see some RPE alterations in fig 5d infrared photograph. (Cyan arrow)

Discussion 

This was a typical case of optic disc pit associated maculopathy (ODP-M) who noticed loss of vision since a month in right eye. On OCT there was presence of intraretinal fluid as well as subretinal fluid which is characteristically seen in ODP-M. There was also presence of an outer lamellar hole which is postulated to be a communication channel between the SRF and IRF. The most common age for presentation of ODP-M is in 3rd or 4th decade of life. 

There are different theories describing the origin of ODP-M fluid. It is thought to be the liquified vitreous which enters into the retinal layers through the retinal or macular hole. The second possible source of fluid is the cerebrospinal fluid (CSF), which has been proposed to enter the intra and sub-retinal spaces from the subarachnoid space through the ODP defect. 

Various treatment modalities have been tried with different success rates. Most common modality of treatment is pars plana vitrectomy with ILM peeling with or without gas injection. Other treatment modalities that have been tried are laser photocoagulation at the temporal disc margin, intravitreal gas injections and macular buckling. We decided to do PPV with ILM peeling and SF6 gas injection in this patient and the patient was followed up post surgery at regular intervals. The intraretinal and subretinal fluid was completely resolved over the period of two years and the visual acuity was improved to 6/9 from 6/36. The resolution of retinal fluid is found to be slower and usually takes 6 months to 2 years in cases of ODP-M. 

Our patient showed gradual resolution with reduction of the retinal elevation over time following surgery. It is difficult to fathom the exact patho-mechanism that results in absorption of the fluid following surgery. It interesting to note that even though in fig. 3b, preoperatively (cyan arrow) and  fig. 5a postoperatively (white arrow) there is  presence of a break in the ellipsoid zone and the outer nuclear layer, with gradual absorption of fluid, these layers appear to connect and rejoin. This suggests an affinity  within the individual retinal layers  to rejoin and realign with themselves. That is to say, that the ellipsoid zone is seen to join with itself and so also the outer nuclear layer.  Even though  the resolution of the retinal elevation took several months and in all likelihood more than a year, there is no significant loss of the ellipsoid zone, while some loss in the interdigitation layer is visible (fig. 5d green arrow). The pre-op visual acuity was 6/36 and  following resolution of the fluid the vision improved to 6/9. This may indicate, that the possibility of photoreceptors retaining function following reduction in subretinal fluid is high. We may explain this by  considering the possibility that the subretinal fluid may not be significantly toxic to the photoreceptors, at least in this particular patient or in such patients.  Other studies mentioned below have also  found good recovery of vision. It is further interesting as to why in the absence of vitreous traction clinically or on OCT, that vitrectomy should help in reduction in the subretinal fluid. There is the possibility that a combination of vitrectomy, ILM peeling with gas injection brings about the changes that are not yet fully understood, but do result in absorption of the fluid and in some way also prevent future  re-accumulation of fluid. 

ReadWise:

  1. Moisseiev, E., Moisseiev, J. & Loewenstein, A. Optic disc pit maculopathy: when and how to treat? A review of the pathogenesis and treatment options. Int J Retin Vitr 1, 13 (2015). https://doi.org/10.1186/s40942-015-0013-8
  2. Hirakata A, Inoue M, Hiraoka T, McCuen II BW. Vitrectomy without laser treatment or gas tamponade for macular detachment associated with an optic disc pit. Ophthalmology. 2012 Apr 1;119(4):810-8. PMID: 22218142 DOI: 10.1016/j.ophtha.2011.09.026

Dr. Sarang Lambat
MS, FRF
Consultant
Vitreoretinal services
Suraj Eye Institute
Nagpur
Email – education@surajeye.org

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