MACULAR CHANGES FOLLOWING PARSPLANA VITRECTOMY FOR RETINAL DETACHMENT USING OCT

MACULAR CHANGES FOLLOWING  PARSPLANA VITRECTOMY FOR RETINAL DETACHMENT USING OCT

By

Abd El- Moez  Haddad  Ahmed; Ahmed  Mohammed  Youssef;

Khaled  Mohammed Selim and  Mostafa  El-sayed  Elewah

Opthalmology  Department  Faculty of  Medicine, Al-Azhar University

ABSTRACT

Background:  Retinal detachment is the separation of  the  neurosensory  retina (NSR) from the underlying retinal pigment epithelium (RPE). These two layers are derived from  neuroectoderm that lines the optic vesicle during embryogenesis.    

Objective:  We compared spectral-domain optical coherence tomography imaging with postoperative visual acuity to evaluate the relationship between morphological changes in the macula  and visual outcome after successful repair of RRD with macula off.

Patients and methods: We enrolled 30  patients (30 eyes) 21 eyes were  phakic (70%) and 9 eyes were pseudophakic (30%).  with successful repair of RRD. the examination had been done 1,2,6-months and one year follow up after surgery in this prospective research.  The mean age of the patients was 17 to 73 years with mean age value of 44 ± 13.4 years.  The duration of  retinal detachment (RD) ranged from 1 to 14 weeks with a mean of 6.8± 4.2 weeks. There was history of trauma in 3 cases (10%). The IS/OS line was evaluated considering its continuity and any disruption in the line was measured by manual caliber. The extent of disruption was evaluated in the 5-lines raster scan. In the scan that showed the largest defect, the extent of the IS/OS disruption was measured along a 1.8 mm-diameter area centered on the fovea.

Results:  SD-OCT was done to all patients post-operatively according to OCT findings, the 30 eyes were divided into three groups; A, B, and C. Group A included all cases with residual subretinal fluid, Group B included cases with other finding rather residual subretinal fluids. Group C included eyes with no detectable OCT findings.

     There were 8 (26.7%) eyes with retained subretinal fluids (Group A), 18 eyes (60%) with pathology other than Subretinal fluid (Group B), and 4 eyes (13.33%) with no detectable pathology after the operation (Group C)

Conclusion: SD-OCT is an irreplaceable instrument for the postoperative assessment of macula in patients who have undergone surgery for macula-off RRD. It permits detection of the presence of foveal changes that are not visible with ophthalmoscope. Persistent sub-retinal fluid is responsible for the poor prognosis after surgery. Although there was a detectable improvement in vision with decrease of the amount of subretinal fluid, Visual prognosis related  to other pathological finding as photoreceptors integrity, and presence or absence of Cystoid macular edema.

INTRODUCTION

     Retinal detachment often is a preventable cause of vision loss. It is defined as separation of the neurosensory retina (NSR) from the underlying pigment epithelium in association with accumula-tion of subretinal fluid (Reichstein et al., 2013).

     A retinal detachment occurs when the forces of adhesion between the neurosen-sory retina (NSR) and the retinal pigment epithelium RPE are overwhelmed. This can occur by different mechanisms. Regardless of the mechanism, all types of retinal detachment have one characteristic in common,i.e. the accumulation of subretinal fluid (Delolme  et al., 2012).

     Despite the high level of anatomic success, visual results remain compro-mised mainly because of permanent functional damage once the macula becomes detached (Kashani et al., 2015).

     Patients with macula-off rhegmato-genous retinal detachments (RRDs) can have poor visual recovery, specific color vision defects, or metamorphopsia postoperatively despite successful retinal reattachment. In these cases, subtle changes in the foveal structure, which may be causing visual disturbances, can be difficult to identify during standard clinical examinations such as slit-lamp biomicroscopy or binocular indirect ophthalmoscopy.

     Wolfensberger and Gonver (2011) reported a possible association between incomplete visual recovery and the presence of residual subretinal fluid (SRF) postoperatively.

     Optical coherence tomography is a noninvasive, patient- and operator-friendly technique that has the advantage of imaging and quantitatively analyzing retinal thickness, nerve fiber layer, and optic nerve structures with good reproducibility (Ricker et al., 2011). The present work aimed to evaluate the relationship between morphological changes in the macula and visual outcome after successful repair of retiinal detachment.

PATIENTS AND METHODS

     This study included some patients suffering from rhegmatogenous retinal detachment with detached macula and Prolirefrative vitroretinopathy( PVR )who attended the outpatient clinic,   AL-Azhar University hospitals (AL-Hussein and Sayed Galal) from October 2012 to May 2015.

    All patients underwent a comprehensive preoperative ophthalmological examina-tion, including complete medical and ophthalmic history, the measurement of best-corrected visual acuity (BCVA), intraocular pressure, slit-lamp anterior  segment examination, indirect ophthalmo-scopy,contact lens slit-lamp biomicro-scopy and fundus photography.

    As all patients were treated with a procedure using silicone oil 1, 000 centistokes which made OCT measure-ments dificult at the early postoperative period   OCT was done at one month for the 1^st time Thus, examinations had been done after 1, 2, 6 months and one year.

Inclusion criteria

     Patients with rhegmatogenous retinal detachment of intermediate severity  of PVR .

Exclusion criteria

■ Recurrent-detachment.

■ Tractional retinal detachment.

■ Strabismus.

■ Glaucoma.

■ Ambylopia.

■ Pre-existing macular disease (e.g. Age related macular degeneration and diabetic retinopathy).

■ Vitreous hemorrhages.

■ Vascular occlusion.

■ Uveitis.

■ Opaque media.

■ Patients with macular hole.

     Patients accepted best-corrected visual acuity examination postoperatively and SD-OCT imaging postoperatively for data analysis and gave written consent. The best-corrected visual acuity was determined from Snellen chart and converted to the logarithm of minimal angle of resolution (log MAR) equivalents to perform the appropriate statistical manipulation The following data collected was age, sex, time from symptom onset to surgery, characteristics of RRD including the number of quadrants involved and proliferative vitreoretinopathy grade.  Central 1 mm subfield retinal thickness (CSFT) was also recorded automatically. This measurement represented the mean distance from the internal limiting membrane to the RPE-Bruch membrane at the fovea. After 6 months, silicone oil was removed in all cases. The retinal status was evaluated again, after silicone removal, with binocular indirect slit-lamp biomicroscopy using contact or non contact lens.

RESULTS

      Thirty eyes of 30 patients were included in this study. The patients were 18 males and 12 females. The male to female ratio was 1.5: 1. The patients' age ranged from 17 to 73 years with mean age value of 44 ± 13.4 years.

Table (1): Age and Sex represent percentage.

     Twenty one eyes were phakic (70%) and 9 eyes were pseudophakic (30%). The extent of RD, types of tears, state of the macula and the grades of PVR were shown in table (2).

Table (2): Clinical data of patients with primary rhegmatogenous retinal detachment.

     SD-OCT was done to all patients post-operatively. According to OCT findings, the 30 eyes were divided into three groups; A, B, and C. Group A included all cases with residual subretinal fluid, Group B included cases with other finding rather residual subretinal fluids, and Group C included eyes with no detectable OCT findings. There were 8 (26.7%) eyes with retained subretinal fluids (Group A), 18 eyes (60%) with pathology other than subretinal fluid (Group B), and 4 eyes (13.33%) with no detectable pathology after the operation (Group C)

SD-OCT was used (Group A) to measure the vertical distance between the center of the fovea and the underlying RPE and considered as the height of the subretinal fluid. Another two perpendicular measure-ments were done to the maximum extent of the elevated fovea. From those two measurements an estimation of the persistence fluid volume was calculated using the ellipse volume formula (Volume = 4/3 π ).

Figure (4): Preoperative optical coherence tomography (OCT) characteristics of the detached neurosensory retina at the macula. A 55-years-old man with a rhegmatogenous retinal detachment (best-corrected visual acuity, 0.06), three months after macular detachment. The detached retina showed multiple small cystic cavities in the inner and outer nuclear layers.

A) SD OCT image obtained after 1 month The IS/OS line was disrupted at the fovea and thickness of the fovea 288µm with BC VA 0.1

B) SD OCT image obtained after 2 months The IS/OS line disrupted mild improved at the fovea and thickness of the fovea was attenuated 276µm with BC VA 0.2.

C)SD OCT image obtained after 6 months The IS/OS line disrupted restored partially at the fovea and thickness of the fovea was mild attenuated 264µm with BC VA 0.6.

Figure (6): Optical coherence tomography (OCT) findings in a 55-year-old man who underwent successful pars plana vitrectomy for a rhegmatogenous retinal detachment.

     OCT examination for( Group B) showed other findings distributed as follows: 5 cases (14.66%) with an epiretinal membrane, one case of cystoid macular edema combined with an epiretinal membrane and 12 cases (26.66%)  with foveal photoreceptor layer disruption.

     Foveal photoreceptor layer pathology was in the form of disruption and/or loss of IS/OS junction.

(Group A):The median and the mean vision for the 8 eyes with sub-retinal fluid in OCT were as follows:

■ After 1 month, the median was 0.6  LogMar (Vision of 0.2 =6/24 snellen chart), and the mean was 0.54±0.21.

■ After 2 month, the median was 0.5 LogMar (Vision of 0.3=6/19 snellen chart), and the mean was 0.41±0.16.

■ After 6 month, the median was 0.4 LogMar (Vision of 0.4=6/15 snellen chart), and the mean was 0.28±0.18 .

■ After one year, the median was 0.3 LogMar (Vision of 0.5=6/12 snellen chart), and the mean was 0.27±0.19.

(Group B): The median and the mean vision for the 18 eyes with other abnormalities rather than sub-retinal fluid was as follow:

■ After 1 month: the median was 0.7 LogMar (Vision of 0.2 =6/30 snellen chart), and the mean was 0.75±0.29.

■ After 2 month: the median was 0.6 LogMar (Vision of 0.25=6/24 snellen chart), and the mean was 0.54±0.24.

■ After 6 months: the median was 0.4 LogMar (Vision of 0.4=6/15 snellen chart), and the mean was 0.38±0.23.

     Vision prognosis was also observed for patients with photoreceptor disruptions and those with macular cysts. Patients with macular cysts showed a better visual acuity (mean vision 0.2 LogMar after 3 months) than cases with photoreceptor disruption (mean vision 0.4 LogMar after 3 months).

(Group C): There were 4 cases with no abnormalities detected in the OCT  The median and the mean vision was as follow:

■ After 1 month: the median was 0.5  LogMar (Vision of 0.32 =6/19 snellen chart) ,and the mean was 0.61±0.24.

■ After 2 month: the median was 0.3  LogMar (Vision of 0.5=6/12 snellen chart), and the mean was 0.36±0.16.

■ After 6 month: the median was 0.2  LogMar (Vision of 0.63=6/9.5 snellen chart), and the mean was 0.17±0.04 .

     Postoperative visual acuity was related to the tomographic results. There were different OCT findings which can be correlated to the bad vision rather than sub-retinal fluid. These were  in the form of photoreceptors disruption and macular cysts. For cases with residual subretinal fluids.

Figure (7): Postoperative amount of macular subretinal fluid after 1m, 2m, 6m and after 1 year

Table (3): Comparison between three groups regarding VA after one, two and  three  months.

DISCUSSION

     In our study, we choosed  patients with RD with proliferative vitreoretinopathy (PVR). Our  results showed complete  postoperative  reattachment in all patients with 95% and single operation  sucsess  rate mean BCVA of 0.69 Snellen chart  (0.2 LogMar)  six months following the surgery.

    Incomplete visual acuity recovery after anatomically and clinically successful repair has been attributed to several preoperative and postoperative factors. Studies proved the effect of clinically detectable pathologic changes such as ERM, cystoid macular edema,  and  persistent macular SRF on reducing postoperative visual acuity (Seo et al., 2008).

     Panozzo et al. (2003) while studying the follow-up period of retinal detach-ments, was the first to observe the presence of small subfoveal lesions,  and considered them as residual detachments of the neuroepithelium related to macular subretinal fluid persistence.

     Studies have shown that clinically invisible pockets of subretinal fluid may persist subfoveally on optical coherence tomography several weeks after successful vitrectomy and gas tamponade (Benson et al., 2006). In our study, we found    26.66%  of subretinal fluid on OCT one month after the surgery in which the visual acuity was 0.6 LogMar.

     Benson et al. (2006) They came with conclusion that persistent SRF 6 weeks after PPV surgery occurs in approximately half of patients, may persist for many months, and can cause delayed visual recovery.

     In our study, the persistent SRF group of cases showed an improvement of vision with decrease of the amount of SRF over time. Also detected other causes of decreased postoperative vision regain.

      Another factor that was suggested to decrease the visual acuity was the formation of postoperative cystoid or spongiform macular thickening (Seo et al., 2008).

     The integrity of photoreceptor outer segments (OS), i.e. the cone OS in the central macular region, could serve as a marker of the health of the cones, The cells  are  primarily responsible for visual acuity (Sheth et al., 2010). In our study the intigrity of IS/ OS junction affected the visual acuity so, we classified into four stages according to the junction .  The IS/OS junction line was intact in 11 (36.66%) eyes, and  V/A ranged between  0.5 and 0.3 LogMar. After 1 month from  mildly disrupted in 4 eyes (25%) ranged from 0.8 to 0.7  LogMar  after  1  month  moderately disrupted IS/OS in 10 eyes (33.% ) ranged from 1.2 to 0.9 LogMar, at 1 month, and severely disrupted  IS/OS in 5 eyes (16.66%) ranged from1.9 to 1.8 LogMar at 1 month The length of  the defect  ranged from 0 in the intact group to 1800µm in the severely disrupted group with a mean of 831±718 micron.

     Although the preoperative duration of a rhegmatogenous retinal detachment (RRD) continues to be an important factor for the postoperative functional prognosis of the eye, it remains controversial  in acute macula-off RRD should be treated as an emergency case (Panozzo et al. (2003).

     In our study, the IS/OS junction line integrity was made as continuous variable by measuring the length of its disruption on raster scans on SD-OCT. There was a moderately strong correlation between the length of IS/OS defect and the visual acuity.

     Many studiesreported use of SD-OCT to investigate changes in the foveal microstructures and correlate it with postoperative visual acuity in patients after anatomically successful repair of RRD. According to these studies, a discontinued IS/OS junction was the most frequent lesion  found in 40% to 82% of patients and was described as a marker of poor prognosis for visual recovery. (Nakanishi et al., 2009;  Wakabayashi et al., 2009; Lai et al., 2010 and Shimoda et al., 2010).

     Our study showed moderately strong correlation between length of IS/OS defect and the duration of retinal detachment (r= 0.602, p= 0.05). A similar correlation was shown by Baba et al. (2008).

     On the other hand, Sheth et al. (2010) showed no significant relationship between the area of IS and OS junction disruption and duration of vision loss before RRD surgery.

     Otani et al. (2010)  published an article on visual recovery in macula-off retinal detachments. In this article he reported that 53% of patients (who could provide adequate information regarding the onset of macular involvement) operated on by 9 days after detachment achieved 20/20 to 20/50 acuity. The proportion attaining 20/20 to 20/50 acuity diminished to 34% in those operated on from days 10 through 19 and to 29%  in those operated on after 19 days. He concluded that patients with macular detachment of 9 days or less had a statistically significant better chance of obtaining final visual acuity of 20/50 or better than those with macular detachment of 10 through 19 days and longer than 20 days duration .

    Wakabashi et al. (2009), performed a non-controlled, prospective, interventional case series on 104 patients with macula-off detachments of 7 days or less .We evaluated the relationship between the central foveal thickness and the post-operative visual outcome where we found a fair inverse correlation between them  Wakabashi et al. (2009) failed to demonstrate a correlation between foveal thickness and visual acuity outcome, but there was no significant correlation with the IS/OS defect.

CONCLUSION

     SD-OCT is an irreplaceable instrument for the postoperative assessment of macula in patients who have undergone surgery for macula-off RRD. It permits detection of the presence of foveal changes that are not visible with ophthalmoscope. Persistent sub-retinal fluid is responsible for the poor prognosis after surgery. Although there was a detectable improvement in vision with decrease of the amount of subretinal fluid, Visual prognosis related  to other pathological finding as photoreceptors integrity, and presence or absence of Cystoid macular edema.

REFERENCES

1. Baba T, Yamamoto S and Arai M  (2008): Correlation of visual recovery and presence of photoreceptor inner/outer segment junction in optical coherence images after successful macular hole repair. Retina, 28 (3): 453-458.

2. Benson SE, Schlottmann PG  and Bunce C (2006): Optical coherence tomography analysis of the macula after vitrectomy surgery for retinal detachment. Ophthalmology, 113 (7): 1179-1183.

3. Delolme MP, Dugas B and  Nicot F(2012): Anatomical and Functional Macular Changes After Rhegmatogenous Retinal Detachment With Macula Off. Am J Opthalmol. 153 (1): 128-136

4. Kashani AH, Cheung AY  and Robinson J(2015)  : Longitudinal optical density analysis of subretinal fluid after surgical repair of  rhegmatogenous retinal detachment. Retina, 35 (1): 149-156

5. Nakanishi H, Hangai M  and  Unoki N (2009):Spectral-domain optical coherence   tomography imaging of the detached macula in rhegmatogenous retinal detachment. Retina, 29 (2): 232-242

6. Otani T, Yamaguchi Y and Kishi S (2010): Correlation between visual acuity and foveal microstructural changes in diabetic macular edema. Retina, 30 (5): 774-780.

7. Panozzo G, Parolini B and  Mercanti A (2003): OCT in the monitoring of visual recovery after uneventful retinal detachment surgery. Semin. Ophthalmol., 18 (2): 82–89

8. Reichstein DA, Larsen BP and  Kim JE. (2013): Management of persistent subretinal fluid following retinal detachment repair. JAMA Ophthalmol.,  (4):132-139.

9. Ricker LJ, Noordzij LJ  and Goezinne F (2011): Persistent subfoveal fluid and increased preoperative foveal thickness impair visual outcome after macula-off retinal detachment repair. Retina, 31 (8): 1505–1512.

10. Seo JH, Woo SJ  and  Park KH (2008) :   Influence of Persistent Submacular Fluid on Visual Outcome After Successful Scleral Buckle Surgery for Macula-off Retinal Detachment. Am J Ophthalmol., 145 (5): 915-922.

11. Sheth S, Dabir S  and  Natarajan S (2010) : Spectral domain-optical coherence tomography study of retinas with a normal foveal contour and thickness after retinal detachment surgery. Retina, 30 (5): 724-732

12. Wakabayashi T, Oshima Y  and Fujimoto H (2009) : Foveal microstructure and visual acuity after retinal detachment repair: imaging analysis by fourier-domain optical coherence tomography. Ophthalmology. 116 (3): 519-528.

13. Wolfensberger TJ and Jules G (2003): Pioneer of retinal detachment surgery. Indian J. Ophthalmol., 51(4):303–308.