Kerala Journal of Ophthalmology

ORIGINAL ARTICLE
Year
: 2018  |  Volume : 30  |  Issue : 1  |  Page : 28--31

Optical coherence tomography characteristics in eyes with optic disc pit with or without maculopathy


Dhileesh P Chandrasekharan 
 Giridhar Eye Institute, Kochi, Kerala, India

Correspondence Address:
Dhileesh P Chandrasekharan
Giridhar Eye Institute, Ponneth Temple Road, Kadavanthra, Kochi, Kerala
India

Abstract

Purpose: The purpose of this study is to study the optical coherence tomography (OCT) characteristics of optic disc pit with or without maculopathy and to validate the mechanism of fluid passage from the optic disc pit to the macula. Materials and Methods: The medical records of 28 patients (28 eyes) with the diagnosis of optic disc pit were reviewed. Clinical features that were studied included the duration of visual impairment, initial visual acuity, and associated fundus features. OCT characteristics including the presence or absence of macular changes, communication with pit, layer (s) of retina involved in schisis, and presence of serous macular detachment (SMD) were noted. Results: The mean age of the patients was 35.32 years. The mean best-corrected visual acuity (BCVA) at presentation was 0.814 ± 0.684 (log of the minimum angle of resolution). Ten of the 28 eyes (35.7) had combined outer and inner layer schisis with no SMD, whereas 6 eyes (21.4%) had combined outer and inner layer schisis with SMD. Four eyes had outer layer schisis only and two eyes presented with outer layer schisis and subretinal fluid. One eye had inner layer schisis alone and one eye had atrophic macula with no schitic changes. Four eyes had no evidence of any maculopathy on OCT. Communication between the schitic cavity to the gap in the lamina cribrosa at the level of the optic pit could be demonstrated on enhanced depth imaging (EDI-OCT) in 14 eyes. The OCT characteristics between the eyes with BCVA >6/12 (Group A) and <6/12 (Group B) were compared. Outer layer retinoschisis was seen in six eyes in Group A compared to 14 eyes in Group B. This was statistically significant (P = 0.044, Fisher's exact test). Mean central macular thickness was 414.5 ± 136.84 μm in Group A and 746.37 ± 433.9 μm in Group B. The difference was statistically significant (P = 0.023, Mann–Whitney U-test). Conclusion: This study validates the hypothesis that cerebrospinal fluid could be the source of fluid in optic disc pit maculopathy as a communication could be demonstrated between the schitic cavity to gap in the lamina cribrosa could be demonstrated on EDI.



How to cite this article:
Chandrasekharan DP. Optical coherence tomography characteristics in eyes with optic disc pit with or without maculopathy.Kerala J Ophthalmol 2018;30:28-31


How to cite this URL:
Chandrasekharan DP. Optical coherence tomography characteristics in eyes with optic disc pit with or without maculopathy. Kerala J Ophthalmol [serial online] 2018 [cited 2021 Jun 13 ];30:28-31
Available from: http://www.kjophthal.com/text.asp?2018/30/1/28/233769


Full Text

 Introduction



Optic nerve head pit was described for the first time by Wiethe in 1882.[1] It is a congenital excavation such as defect of the optic nerve head. Optic nerve head pits occur mostly at the temporal side of the optic disc and are bilateral in 10%–15% of cases.[2],[3] About 20% of the cases retain reasonably good visual acuity of more than 0.75. Patients with optic pits do not usually have any visual complaints until changes in the macular region develop, generally at the age of 21–30 years.[4] Because of the low prevalence of the disease, controversies exist concerning the origin of fluid and mechanism of optic disc pit-associated maculopathy. Furthermore, due to the relative rarity of the disease, there are no prospective studies or clear-cut guidelines on the nature and timing of treatment of optic nerve head pit maculopathy. However, we do have wealth of information from previous retrospective studies about the nature and progression of the disease. We would like to add to the existing knowledge based on optic nerve head pit maculopathy and possibly guide future studies on the same. The aim of our study was to study the spectral domain optical coherence tomography (OCT) characteristics of eyes with optic nerve head pit with or without maculopathy. We also attempted to correlate the presenting visual acuity with the OCT findings in cases with optic nerve head pit.

 Materials and Methods



The case records of all 28 consecutive patients who had optic pit with or without maculopathy and who had undergone OCT (Heidelberg Spectralis) during the period between January 2013 and May 2017 at a tertiary care institute were reviewed. All patients who had undergone previous treatment for optic nerve head pit maculopathy were excluded from the study. All patients underwent comprehensive eye examination including fundus photographs and OCT. The line scan, ranged from 2 to 8 mm in length, at various angles was used through the optic pit to visualize a possible communication between the optic pit and neurosensory retina; the macular thickness scan was done to demonstrate the retinal layer schisis and retinal detachment. Fluid accumulation at the level of outer plexiform layer and/or outer nuclear layer was defined as outer layer retinoschisis (OLR) and fluid collection at the level of nerve fiber layer and/or ganglion cell layer was defined as inner layer retinoschisis (ILR). Fluid between retinal pigment epithelium and neurosensory retina were defined as serous macular detachment (SMD). Enhanced depth imaging-OCT (EDI-OCT) was used to demonstrate the communication between the pit and schitic spaces/subretinal fluid wherever possible. Statistical analysis was performed using statistical software SPSS version 16 (SPSS Inc., Chicago, IL, USA).

 Results



Twenty-eight eyes of 28 patients were included in the study [Table 1]. The mean age of the patients was 35.32 ± 20.7 years (range-8–75 years). Thirteen (46.4%) of the patientswere male and 15 (53.6%) were female. The right eye of the patient was affected in 13 cases and the left eye in 15 cases. No case of bilaterality was noted. The mean best-corrected visual acuity (BCVA) at presentation was 0.814 ± 0.684 (log of the minimum angle of resolution). Ten of the 28 eyes (35.7%) had combined outer and inner layer schisis (OLR + ILR) with no SMD [Figure 1] and [Table 2], whereas six eyes (21.4%) had combined outer and inner layer schisis with SMD (OLR + ILR + SMD) [Figure 2]. Four eyes had outer layer schisis (OLR) only [Figure 3] and two eyes presented with outer layer schisis and SMD (OLR + SMD) [Figure 4]. One eye had inner layer schisis alone (ILR) and one eye had atrophic macula with no schitic changes. Four eyes had no evidence of any maculopathy on OCT. The mean central macular thickness (CMT) was found to be 604.14 ± 374.46 μm. Communication between the schitic cavity to the gap in the lamina cribrosa at the level of the optic pit could be demonstrated on EDI-OCT in 14 eyes [Figure 5].{Table 1}{Figure 1}{Table 2}{Figure 2}{Figure 3}{Figure 4}{Figure 5}

The eyes were divided into two subgroups based on BCVA at presentation [Table 3]. Group A where the initial BCVA was 6/12 or better (0.3 logMAR) and Group A with BCVA <6/12. There were 12 eyes in Group A and 16 in Group B, respectively. The OCT characteristics between the two subgroups were compared. In Group A, two eyes showed SMD compared to six eyes in Group B. This was not statistically significant (P = 0.402, Fisher's exact test). Outer retinal schisis (OLR) was seen in six eyes in Group A compared to 14 eyes in Group B. This was statistically significant (P = 0.044, Fisher's exact test). Mean CMT was 414.5 ± 136.84 μm in Group A and 746.37 ± 433.9 μm in Group B. The difference was statistically significant (P = 0.023, Mann–Whitney U-test). Other OCT parameters such as inner layer schisis, retinal pigment epithelium atrophy, ellipsoid zone loss, and epiretinal membrane did not show any significant difference between the two groups.{Table 3}

 Discussion



The previous studies on OCT findings in optic nerve head pit have demonstrated the typical findings of outer layer retinoschisis (OLR), ILR, and SMD and described the frequency of these findings [Table 4]. Krivoy et al. studied eight eyes and showed that OLR alone was seen in one eye, ILR alone in two eyes, OLR + ILR in two eyes, and OLR + ILR + SMD in three eyes.[5] Imamura et al. showed in a study of 16 eyes that OLR + ILR was seen in five eyes, OLR + SMD in seven eyes, OLR + ILR + SMD in three eyes, and SMD alone in two eyes.[6] In a study on Indian eyes, Roy et al. demonstrated the presence of OLR + ILR in 1 eye, OLR + SMD in 12 eyes, OLR + ILR + SMD in 17 eyes, and OLR alone in 2 eyes.[7] Our study found OLR + ILR in 10 eyes, OLR + ILR + SMD in 6 eyes, OLR + SMD in 2 eyes, OLR alone in 4 eyes, ILR alone in 1 eyes, and atrophic macula in 1 eye.{Table 4}

We could demonstrate the communication of the schitic cavities to the 14 of the 28 eyes. This supports the hypothesis that the origin of fluid in optic nerve head pit maculopathy is cerebrospinal fluid. This is a higher number than that described by previous studies. Roy et al. demonstrated the communication in 34% of their study eyes.[7] This can probably be attributed to the use of EDI with spectral domain OCT because most of the earlier studies where on time-domain OCT. We observed that CMT has a negative correlation with visual acuity. SMD involving the fovea along with decreased vision has been the traditional indication for treatment in optic nerve head pit maculopathy. Surprisingly, we could not find a statistically significant correlation between SMD and visual acuity. This could be attributed to the low frequency of SMD that we came across in our study. Furthermore, interestingly we found that outer retinal schisis showed significant correlation with visual acuity. We suggest that outer layer retinoschisis may also be an indication of treatment in optic nerve head pit maculopathy and suggest further prospective studies in this direction.

The limitations of our study include the retrospective nature of the data. The data were collected at the time of presentation. Hence, the OCT findings may vary according to the stage of the disease in the individual at the time of presentation. This might have also affected the outcome.

 Conclusion



We have described the spectral domain OCT findings in 28 eyes with optic nerve head pit. We could demonstrate a communication between the pit and schitic cavities in 14 eyes. This supports the hypothesis that the origin of fluid in ONH pit maculopathy is cerebrospinal fluid. We found that higher CMT and presence of outer layer retinoschisis are the most consistent predictors of poor visual acuity in optic disc maculopathy. We suggest further prospective studies to evaluate the need of treatment with respect to OCT findings.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.[8]

References

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