Anatomical and functional outcome of surgical correction of optic disc pit maculopathy using autologous scleral patch graft: a long-term retrospective analysis

Abstract

Background

Optic disc pit (ODP) is a rare congenital anomaly of optic nerve head and is associated with maculopathy. Scleral patch graft (SPG) as a therapeutic option is recently advocated.

Methods

This is a retrospective analysis of 54 patients with ODP maculopathy who were followed up for 12 months post-operatively. The parameters assessed included best corrected visual acuity (BCVA) in LogMAR chart and central macular thickness (CMT) at baseline and at 1-, 3- and 12-months post-surgery.

Results

The mean age of presentation was 36.36 ± 15.69 years [Median 36, Interquartile range (IQR) 14.75]. 51.85% were female. 53.7% were operated in left eye. The average period of follow-up was 15.37 ± 2.34 months after surgery. The mean presenting BCVA in LogMAR chart was 0.66 ± 0.37 (Median 0.6, IQR 0.4) and average CMT was 677.46 ± 251.57µ (Median 674, IQR 276). On follow up over 1, 3 and 12 months, average BCVA were 0.74, 0.58 and 0.49 LogMAR respectively. The improvement in final BCVA was statistically significant (p = 0.016). The CMT at the corresponding follow-up periods were 461.26 ± 238.3µ (Median 435, IQR 220.5), 362.68 ± 125µ (Median 367, IQR 141) and 287.36 ± 121.9µ (Median 266, IQR 139.5). Decrease in CMT was significant at all follow up visits (p < 0.001). On assessing OCT Biomarkers, Subretinal fluid (57.4%), Intraretinal Fluid (57.4%), macular schitic cavity (79.63%), Outer Lamellar Macular hole (31.48%), Pachychoroid vessels (35.19%), Outer Retinal Layer Disruptions (24.07%) were present in various proportions on presentation. After surgery over the follow-up, retinal fluid and schitic cavities were observed to get regressed over time. Outer Lamellar Macular holes showed excellent regression after surgery over a period of time. On final visit after 1 year of surgery, complete anatomical success in terms of OCT interpretation was achieved in 16 cases (29.63%). Partial anatomical success was achieved in further 24 cases (44.44%). At least some anatomical improvement was seen in 49 patients while in 3 patients it remained almost unaltered and 2 cases worsened. Successful visual rehabilitation was achieved in 45 patients (83.33%)

Conclusions

Detailed OCT based and functional analysis in this study with long-term follow-up helps to entitle the importance of scleral patch graft based surgical procedure in managing this challenging surgical condition. This article caters the largest case series with meticulous analyses of the ODP Maculopathy surgically managed using autologous scleral plug.

Background

Optic Disc Pit (ODP) is a rare congenital abnormality of the optic nerve head [1]. Optic disc pits are considered as part of a spectrum of congenital cavitary anomalies of the optic disc, which also includes optic disc coloboma, morning glory and extra-papillary cavitation [2]. It typically appears as a unilateral, small, oval, hypo-pigmented grey–white excavation of the optic disk, most commonly located at the temporal or inferotemporal segment of the optic disk, although it can be rarely found centrally or along the nasal side of the optic disk, while 15% of ODP were found to be bilateral [1, 3].

The entity is rare (less than 1 in 10,000 patients seen in the ophthalmic setting) and about 30–75% of cases have a concurrent serous detachment of the macula [4]. With chronic serous detachment, precipitates may occur on the posterior surface of the retina, and chronic cystoid changes appear in the fovea. The source of the subretinal fluid is controversial, and it is suggested that the detachment may involve the passage of vitreous fluid from the area of the pit to the subretinal space. Other sources of fluid may be abnormal blood vessels at the base of the pit or subarachnoid space [5]. Recent publications have suggested that both posterior vitreous detachment and macular traction play a vital role in the pathogenesis of optic disc pit maculopathy [6]. Lincoff and colleagues [7] proposed that fluid from the optic disc pit creates a schisis-like inner layer separation of the retina and the detachment at the outer layer of the macula is a secondary phenomenon.

The long-term visual prognosis in patients with optic nerve pit and untreated Optic Disc Pit Maculopathy (ODPM) is generally poor. The reduced visual acuity usually occurs after 6 months of the onset of the serous macular detachment [8]. Spontaneous resolution of ODPM was also described after completion of Posterior Vitreous Detachment (PVD) [9]. Role of Pars Plana Vitrectomy (PPV) with various surgical adjuvants like endo-laser and gas injection have been published [10]. Recently, authors have used fibrin glue, Internal Limiting Membrane (ILM) grafts and scleral grafts for plugging the pit with variable results [11].

In this article, we have discussed our vast experience of a decade regarding surgical correction of ODPM with the help of scleral patch graft closure of the defect. The unique surgical technique and promising results will help enlighten the management of this rare entity.

Methods

This retrospective study was done at a tertiary care ophthalmological institute in southern part of India. Records of all the patients who underwent vitrectomy for ODP maculopathy along with closure of the pit with scleral plugging from January 2016 to December 2022 were reviewed. All the surgeries were performed by a single surgeon (NB).

The patients who underwent vitrectomy for ODPM were included in the study. Those with axial length < 22 mm or > 24 mm (to exclude any refractive status related retinal changes e.g., uveal effusion syndrome, myopic macular degeneration, myopic traction maculopathy etc., that may affect the final outcome), any coexisting ocular pathologies affecting vision and those lost to follow-up before one year were excluded from the study. All the patients included in our study were received as treatment naïve cases in our institution and after a battery of investigations, were decided to be posted for surgical correction.

All the patients underwent complete ophthalmological examination including Best-Corrected Visual Acuity (BCVA), Intraocular Pressure (IOP), slit-lamp biomicroscopy, dilated fundus examination and Optical Coherence Tomography (OCT) at baseline and all follow-up visits. BCVA was converted into logarithm of the minimum angle of resolution (logMAR) for statistical analysis [12, 13]. Spectral-domain OCT (Heidelberg Retina Angiograph-Optical Coherence Tomography; Heidelberg Engineering, Heidelberg, Germany) centred on the fovea and optic disc was done using high-definition 5-line raster scans and three-dimensional 512 × 128 macular cube scans passing through fovea and optic disc. The maximum subretinal fluid (SRF) present between the two arcades was measured. The built-in software was used to produce retinal thickness maps, which were averaged over nine retinal subfields in a 6 mm diameter circle centred on the fovea. The central foveal thickness was measured from the subfield bounded by the innermost 1 mm diameter circle [14].

The patients were examined at postoperative day 1, 2 weeks, 1month, 3 months and then 3-monthly. Frequent follow-ups were scheduled in case of any complication. The patients were followed up for at least 1year. The results were evaluated at the end of 1year. Three patients were removed from all calculations as they were irregular during the post-operative period as per scheduled follow-ups. Two of them completed 7-months and 9-months follow-up before getting lost to follow-up and they showed partial recovery till the last visit. One patient was lost to follow-up only after the first post-operative visit. In all the three cases surgery went uneventful.

Complete anatomical success was defined as total resolution of all the fluid in retinal compartments, that is, SRF, Intraretinal Fluid (IRF) and macular schisis on OCT. By definition, SRF was defined in the study as collection of fluid in between neurosensory retina and retinal pigment epithelium. While IRF was defined as accumulation of fluid within the retina in the form of cystic changes, spongiform changes involving predominantly inner retinal layers. Schisis was defined as a separation of the neurosensory retina into two or more layers in the foveal area with prominent muller cell processes giving rise to a characteristic OCT pattern (Fig. 1).

Fig. 1

These pair of representative images showing comparison of Pre-operative and Final visit OCT images of the cases where pre-operatively patients presented with schitic macular cavities, intraretinal fluid and subretinal fluid and on surgical correction demonstrated complete resolution of all kinds of retinal edema. These cases represent “Complete Anatomical Success”

Partial success was defined as a reduction in Central Foveal Thickness (CFT) with residual SRF, IRF or schisis on OCT. Visual success was defined as a gain of at least 2 Snellen lines.

Surgical technique

All the patients underwent 25G PPV. To ensure its complete removal, vitreous was stained with triamcinolone acetate (Aurocort; Aurolab, India) before induction of posterior vitreous detachment. ILM was stained with 0.05% brilliant blue G (BBG) dye and peeled in a circular fashion for approximately 2-disc diameters around the fovea. Fluid–air exchange (FAE) and active internal SRF drainage through the pit were done. Although we did not quantitate the amount of residual SRF on intra-operative OCT, we tried to drain as much subretinal fluid as possible and continued till a flattening of macular elevation was observed. Postoperative tamponade was provided with Sulphur Hexafluoride (SF₆) gas and advised prone positioning for one week. Endo-laser or retinotomy to drain fluid was not done in any case. In all patients, a 1 mm×1 mm homologous partial-thickness scleral flaps was crafted from inferonasal quadrant of the ipsilateral eye. One of the 25G trocar–cannula systems was replaced with the 23G non-valved system and the scleral plug (SP) was introduced into the vitreous cavity. The scleral flap was then tucked into the pit using a Tano diamond dusted membrane scraper (Tano DDMS) or with help of atraumatic haptic-holding forceps. In all cases, careful fluid-air exchange was done nasal to the disc so as to avoid flap dislodgement. The ILM flap being BBG-stained and scleral flap being opaque could be visualised under air. In occasional instances where the flap slipped out of the pit, it was again tucked back into the pit.

Statistical analysis

Statistical analysis was performed with STATA statistical software, V.14.0 (StataCorp, College Station, Texas, USA). Continuous variables were expressed as mean ± SD. Whereas, in cases of non-normalized data, the median value and the interquartile range (IQR) was mentioned along with mean ± SD (Median ± IQR). Categorical data were described in percentages. Independent Student’s t-test, Mann-Whitney U test or Wilcoxon signed-rank test was used to find out the difference between two continuous variables. χ2 or Fisher’s exact test was used to find out the difference between two noncontinuous variables. P value less than 0.05 was considered to be statistically significant.

Results

The study included retrospective data of 54 eyes of 54 patients who underwent surgical correction of ODPM involving scleral patch graft in that stipulated time period, excluding all the cases those were not fit as per our study design. Out of 54 patients, 28 (51.85%) were female and rest were male. The mean age was 36.36 ± 15.69 years (36 ± 14.75, Range, 10–74 years). Based on laterality, 53.7% of patients presented with symptoms in left eye (OS) and 46.3% of patients in right eye (OD). The mean IOP was 16.17 ± 2.59 mmHg (Range, 10–24 mmHg). None of the patients received any sort of treatment for the diagnosed ODP. Out of 54 patients, 51 were phakic and none of them had any significant cataract that needed treatment on presentation along with the management of the maculopathy. 3 patients were pseudophakic prior to the presentation without any significant posterior capsular opacification.

After presentation, all the patients underwent surgical correction within a couple of weeks. Median waiting period was 7.45 ± 5.64 days (7 ± 5). The average period of follow-up was 15.37 ± 2.34 months after surgery. On baseline evaluation presenting BCVA was 0.66 ± 0.37 (0.6 ± 0.4) on LogMAR chart. On OCT analysis, mean Central Macular Thickness (CMT) was 677.46 ± 251.57µ (674 ± 276µ). All the patients were followed up on regular interval and post operative 1 month, 3 months and 1 year data were utilized for calculation purpose. On these aforementioned follow-ups the BCVA on LogMAR chart were 0.74 ± 0.34 (0.8 ± 0.5), 0.58 ± 0.33(0.6 ± 0.4) and 0.49 ± 0.32 (0.5 ± 0.3) units respectively. The CMT at the corresponding follow-up periods were 461.26 ± 238.3µ (435 ± 220.5µ), 362.68 ± 125µ (367 ± 141µ) and 287.36 ± 121.9µ (266 ± 139.5µ) (Table 1).

Table 1 Table depicts the trend of average functional outcome in terms of BCVA and average anatomical outcome in terms of CMT from presentation till last visit after at least 1 year of surgery

On detailed interpretation of the OCT images of the cases, it was seen that SRF, IRF and Schitic edema were present in different proportions in all cases. 31 patients out of all cases (57.4%) had IRF and SRF each while 43 cases (79.63%) had schitic edema on presentation. Of all the cases those had SRF, Subretinal precipitates as hyperreflective dots on the under surface of photoreceptors.

On further detailing, 17 cases (31.48%) had outer lamellar macular hole while one patient had full thickness macular hole (FTMH).

Thirteen patients (24.07%) had External Limiting Membrane/ Ellipsoid Zone disruption on presentation. 19 patients (35.19%) presented with coexisting Pachychoroid vessels in the subfoveal region.

Complete anatomical success was defined as complete resolution of any types of SRF, IRF or schitic fluid with complete closure of the optic disc pit and regaining normal foveal contour. Partial anatomical success was defined as achieving subfoveal CMT less than 300µ with maximum resolution of retinal edema with definite closure of the pit completely. Successful visual rehabilitation was defined as gain of at least 2 lines in Snellen’s chart on final visit. On final visit after 1 year of surgery, complete anatomical success in terms of OCT interpretation was achieved in 16 cases (29.63%). Partial anatomical success was achieved in further 24 cases (44.44%). At least some anatomical improvement was seen in 49 patients while in 3 patients it remained almost unaltered and 2 cases worsened (Fig. 2).

Fig. 2

These three cases of pre-operative and final visit comparisons where patients presented with ODPM and even after meticulous surgical correction using autologous scleral patch graft to cover the ODP, insignificant visual and anatomical improvement were recorded

Successful visual rehabilitation was achieved in 45 patients (83.33%). Two patients developed full thickness macular hole and did not show any improvement in visual acuity while the patient presented with full thickness macular hole had a successful closure with significant anatomical and functional benefit. The patients who developed full thickness macular hole (FTMH) after surgery experienced a significant deterioration in visual acuity. One of them achieved a final visual acuity of 2/60 on Snellen’s chart from 6/36 while the other patient could read till 3/60 in the final follow-up compared to 6/60 during pre-operative phase (Fig. 3).

Fig. 3

This pair of images show a particular case of ODPM where patient presented with a Full Thickness Macular hole (FTMH) on presentation and after surgical correction showed “Complete Anatomical Success”

On final follow-up it was noted that schitic fluid was completely resolved in 38 patients out of 43 patients (88.37%). SRF and IRF was completely resolved in 21 patients (67.74%) and 19 patients (61.29%).

Patients with outer lamellar macular hole on presentation had an excellent outcome at the end of 12 months follow-up and 13 of those patients (76.47%) achieved near-normal foveal contour with significant increase in neurosensory retinal thickness in subfoveal plane. These patients have significantly achieved successful visual rehabilitation. It is also noted that persistence of pachychoroid at the end of 1 year have significantly influenced the resolution of retinal edema (Fig. 4).

Fig. 4

Representative images showing comparison of outcome from pre-operative to final visit of patients presenting with Outer Lamellar Macular hole and after surgical correction showing complete resolution

Discussion

The purpose of treatment of ODPM is to produce a permanent barrier for fluid migration out of the ODP. While vitrectomy and ILM peeling relieve the various anteroposterior and tangential tractions, juxtapapillary laser photocoagulation produces a scar to prevent the intraretinal and subretinal fluid migration. It has been proposed that sealing the pit may permanently close the source of fluid, that is, the pit itself [3, 6].

We evaluated the surgical outcome of 54 patients with ODPM over 12 months retrospectively and thoroughly analysed the data gathered regarding the utility of the surgical procedure. 49 patients demonstrated at least some anatomical improvement over the time period while three patients worsened even after successful surgical management and two other developed FTMH at the end of follow-up.

On evaluating resolution of CMT over 1,3 and 12 months, the improvement is statistically significant at all instances (p < 0.001). While assessing improvement in BCVA it was observed that improvement at 1 and 3 months were not statistically significant (p = 0.25 and p = 0.23 respectively). However, at 12-month follow-up the improvement in BCVA was statistically significant (p = 0.016).

Similar to that reported in literature, the residual SRF in eyes with partial anatomical success shifted inferiorly along the vascular arcade [18]. Hirakata et al. proposed that this shift may be due to the fact that the fluid in ODPM may have migrated along the vessels. Thus, incomplete resolution may have shifted the fluid back to the vicinity of the vessels [15, 16].

The use of autologous scleral patch to seal the ODP was first proposed by Travassos et al. [17]. They reported three cases, one with previous failed vitrectomy and two treatment-naive, which showed fluid resolution and visual gain after 12 months of surgery [17]. Shah et al. reported two cases of treatment-naive eyes successfully treated with SP and gas tamponade. In both series, the scleral patch remained in correct position even after 2 years of surgery [18].

A prior publication of one of the authors compared the efficacy of ILM plugging versus autologous scleral plugging of the ODP as an adjunct with conventional vitrectomy and ILM peeling for surgical correction of ODPM [19]. In that article, results reflected that both ILM plugging and autologous scleral plugging of the pit delivered similar results and achieved 85.7% and 87.5% anatomical correction rate at the end of 1 year [19]. In our study anatomical betterment in terms of ‘complete’ anatomical success and ‘partial’ anatomical success after 12 months was 74.07%. 90.74% of patients at least ‘some’ anatomical betterment. When calculated in terms of improvement in vision, it showed 83.33% betterment at the end of 12-month follow-up. The authors declare that none of the patients’ data from this prior publication were utilized in this current retrospective study. A comparison of the results of previous landmark publications and our results are described in tabular form herewith (Table 2).

Table 2 Comparative analysis of the previous studies on management of optic disc pit maculopathy with the present study

Shukla et al. reported the transition to FTMH in more than 50% cases after peeling ILM in the presence of Outer lamellar macular hole [26]. In our earlier article, out of 11 patients with Outer lamellar macular hole only one patient developed FTMH [19]. In this series, out of 17 patients with Outer lamellar macular hole only one developed FTMH and 3 of them did not improve even after meticulous surgical management (Fig. 5).

Fig. 5

The two cases where patients presented with ODP-M and even after adequate surgical correction, developed Full thickness Macular hole on post-operative period, leading to poor functional outcome

Limitations of this study include its retrospective nature, relatively shorter follow-up, non-evaluation of visual field changes post-surgery as it may have damaged retinal nerve fibre layer while plugging the scleral patch graft inside the pit. Although a randomised controlled trial with a larger sample size is recommended, performing such a trial is difficult due to the low incidence of the disease.

Conclusion

This article caters the largest case series of the ODPM with surgical correction using autologous scleral plug with meticulous analyses. We have not only shown the outcome in terms of difference in CMT or improvement in BCVA but also with the microstructural changes of the central macula in OCT. We found that the surgical technique is in line with the previous studies in terms of visual betterment and improvement of CMT and gives satisfactory results on long-term follow-up. Also, our cases have shown exciting post-operative results in patients presenting with Outer lamellar macular holes. However, cases with persistent Pachychoroid have drawn poor outcomes in terms of the resolution of retinal edema.

We hope our observation will help to choose the aforementioned surgical technique as a useful one in managing this challenging rare scenario in the future.