Dr.Pranita Chaudhary, P19932, Dr.Jayesh Khandelwal, Dr.Navneet Mehrotra, Dr.Manish Nagpal

Abstarct:

Aim:

To evaluate the outcomes of CASB in primary rhegmatogenous retinal detachment (RRD).

Methods:

Retrospective analysis of 98 cases with RRD undergoing CASB was performed. Complete examination with characteristics of RRD were noted. Intra-operative details were correlated with preoperative findings. Anatomical & functional outcomes were evaluated with a minimum follow up of 4 years.

Results:

Mean BCVA improved from 0.83 to 0.29 logMAR post operatively. 15(15.3%) eyes showed re-RD, with an average interval of 4.18 months from the primary surgery.Causes of re- RD were missed breaks in 2 eyes, new breaks in 6, proliferative vitreoretinopathy in 5 & no identifiable cause in rest. All eyes had successful reattachment of the retina after vitrectomy.

Conclusion:

CASB is an effective alternative to indirect ophthalmoscope assisted SB in RRD with comparable results & an added advantage of enhanced microscopic magnification & wide field illumination along with ergonomic benefits.

INTRODUCTION

Rhegmatogenous retinal detachments (RRD) is an important cause of severe and permanent vision loss. Surgical procedures include scleral buckling, pars planavitrectomy (PPV), pneumatic retinopexy or a combined vitrectomy with scleral buckling (SB).¹

Various studies have tried to evaluate the outcomes of primary vitrectomy versus scleral buckling. Of these, the biggest study has been the SPR study.

Moreover, the inability of students to observe the various steps of buckling during surgery due to use of intraoperative indirect ophthalmoscopy in SB limits its transfer to vitreoretinal fellows.

The recent advances in the vitrectomy machines,wide-angle viewing systems (WAVs) make PPV a more attractive and comfortable option.

Chandelier assisted scleral buckling combines the advantages of both SB and vitrectomy to provide us with optimal surgical outcomes. It capitalizes on advances in visualization technology afforded by WAVs through the operating microscope, while maintaining the technical simplicity of the procedure as SB.

In our pilot study, we presented a short series of cases emphasizing on not only the surgical benefits of the procedure, but also its educational and ability to provide comfort to the operating surgeon.³Since then, various other reports in literature shows chandelier assisted scleral buckling as a promising surgical technique but limited data regarding long-term outcomes of this technique exists.^4-8

We present a series of cases that underwent SB under microscope using Volk HRX Vit SSV lens (VOLK, Mentor, Ohio) using a single 25-gauge chandelier (ALCON, Fort Worth, Tex) for illumination.

Materials and methods:

We included 82 eyes with RRD with peripheral breaks, suitable for scleral buckling surgery.

Preoperative ophthalmic examination was carried out, including the following: best corrected visual acuity (BCVA) assessment, anterior segment examination, intraocular pressure (IOP) measurement usingnon-contact tonometry.Funduswas examined using slit lamp biomicroscopy and indirect ophthalmoscope.Amsler Dubois chart was used for detailed charting of the fundus.

Informed consent was obtained after explanation of the procedure.

Operative procedure included the following:

Under general or peribulbaranaesthesia, 360° conjunctival peritomy was performed with traction sutures under the recti using 2-0Mersilk sutures. Sclera was examined for areas of thinning and for abnormal positions of the vortex veins. A non valved 25 G trocar cannula was inserted about 180° away from the preoperatively determined retinal break(s), 3 mm, 3.5 mm and 4 mm away from the limbusin aphakic, pseudophakic and phakic patients respectively. Next, a 25 G chandelier light (Chandelier Lighting System; Alcon, Fort Worth, Texas, USA) was inserted into the cannula.Once the chandelier was inserted, the wide-field viewing contact lens Volk HRX Vit SSV was placed. After reinverting the image, fundus was examined thoroughly using indentation and the break/s were localized. Cryopexyof the breaks and all the suspicious areas was performed. Silicone sponge 5 mm 506 (LABTICIAN Ophthalmics, Inc, Oakville, Ontario, Canada) was passed beneath the rectus muscles and fixed withMersilene (5-0) suture placed in the sclera. The buckle was placed in a segmental or circumferential manner depending on the site of the break. Whenever not necessary, chandelier fibre-optic was removed and the cannula plugged. Reinsertion of the chandelier fibre-optic to judge the height of the buckle was done, the need for subretinal fluid drainage and/or tamponading gas.Subretinal fluid was externally drained through a sclerotomywith a 24-gauge needle after diathermy to the sclerotomy site. Chandelier fibre optic wasremoved andthe sclerotomy site was sutured whenever required to prevent vitreous leak. Conjunctival closure was performed using 8-0 vicryl after instillation of povidone iodine.All surgeries were transmitted real time to the viewing monitor within the theatre for visibility to fellows/assistants, and the entire surgical procedure was recorded for teaching and training purposes.

Patients were followed up post operativelyon day 1 and at months 1, 6 and 12. During, each visit,best-corrected visual acuity (BCVA), intraocular pressures,anatomical and functional status of the retina was assessed.

Results:

Medical records of 82 patients were retrospectivelyanalysed in the study. The average age of patients was 28.53 years and with a male preponderance (76.8%). The mean duration of follow-up was 12.3 months (range: 12–36 months). Amongst the cases, 78 were phakic, 2 were aphakic and 2 pseudophakics.The duration of the symptoms ranged from 1 day to 3 months. Incidence of PVR was 14.63% (12 eyes).

Number of eyes having macula-involving RD were 69.51% (57). On pre-operative assessment, RRD due to single break in 51 eyes (68.29%) and 2 breaks in 14 eyes (17.07%), multiple breaks in 11 eyes (13.41%). Pre operatively break was not visualised in 6 eyes despite a thorough fundus examination.The RD involved more than 2 quadrants in 62 eyes.Pre-operative mean BCVA was 0.83 logMAR.

Number of patients	98
Age range (years)	7 to 50
Mean	28.53
Gender (Males)	63
Predisposing Factors Myopia	42
Trauma	15
Laterality Right Eye	48
Follow-up periods (months)	12-36
Mean	12.3
BCVA (logMAR)	0.83
Number of Breaks One	55
Two	18
>2	15
Not visualised	10
Location of retinal breaks
Limited to superior quadrants	36
Limited to inferior quadrants	26
Both superior and inferior quadrants	4
Extent of retinal detachment
<2 quadrants	20
≥ 2 quadrants	62
Macular detachment	57 (69.51%)

 

Table 1: Pre-operative Demographics of patients.

An encircling buckle was done in 58 eyes, and segmental buckle used in 42eyes. Subretinal fluid was drained in all cases.Vitreous leak occurred in 12 eyes after removing the trocar. Sclerotomies were sutured with 8-0 vicryl in all cases.

Inferonasal Quadrant	8
Inferotemporal Quadrant	73
Superotemporal Quadrant	11
Superonasal Quadrant	6

Table 2: Site of insertion of Chandelier tip

On post-operative day 1, 87 eyes (89.02 %) had attached retina and 9 eyes (8.53 %) hadsubretinal fluid. None of the eyes had postoperative leak, hypotony or chandelier site related break or cataract.
One month after the surgery, the BCVA ranged from 4\60 to 6\6 with a mean of 0.32logMAR. 7 eyes showed delayed absorption of subretinal fluid with attached retina.2 eyes had persistent RD due to non-closure of the break and underwent PPV with silicon oil injection.

Finally, 6 months after the surgery, the BCVA improved marginally with a mean of 0.29logMAR.

In the period of 4 years follow up, 15 eyes showed re-RD, with an average interval of 8.3 months between the primary scleral buckling surgery and re-RD. The primary reattachment rate at the end of 1 year was 85.7%. Cause of re- RD was development of new break in 5 eyes, PVR with traction on inferior retina in 6 eyes and no apparent identifiable cause in rest of the eyes. PPV was performed with membrane removal, endolaser and silicon injection.All eyes had successful reattachment of the retina after vitrectomy.One patient developed a new break with surrounding subretinal fluid that was barraged with laser photocoagulation. 4 eyes had a transient increase in intraocular pressure postoperatively, which was treated with topical antiglaucoma medications.

 Discussion:

 Before the turn of the 20th century, contrary to other branches of ophthalmology, the surgical treatment of retinal detachment was still in its infancy, and the surgical success rates were less than five percent. Scleral buckling has been successfully employed to repair rhegmatogenous retinal detachments for over 60 years.

However, with the advent of vitrectomy and recent introduction of microincision vitrectomy surgery, scleral buckling is declining in popularity.  Conventionally, indirect ophthalmoscope with a handheld convex lens has been used for fundus visualization, which provides inverted, laterally reversed image of the fundus with a low magnification. This requires skill and experience at every step, from localizing the tears to indenting the sclera and draining the subretinal fluids. Moreover, repetitive wearing and removal of an indirect ophthalmoscope is cumbersome.

Previously, literature on endoillumination-assisted buckling have reported the use of wide-angle viewing systems instead of the indirect ophthalmoscope with better visualization potentials. This technique provides a straight image of the fundus, allows magnification of suspicious breaks for confirmation without compromising the peripheral view, thus facilitating the scleral buckling surgery. The ergonomic benefits for the surgeon in the long run to do buckling procedures with the comfort of sitting on a chair and its educational value has already been looked at in previous studies.

WAVs may be contact or non- contact type. Though the choice of WAVs depends on the surgeon’s preference, both types have pros and cons.

Most studies in the past have used a non-contact method for endoillumination-assisted buckling.^4,7,8 Whereas, contact WAVs provide superior imaging resolution, are cheaper and do not require mounting on the microscope, buckling under the microscope with a contact lens can prove challenging due to the difficulty to manoeuvre the globe and placement of the cryo probe.

Nam et al  earlier performed scleral buckling using a surgical microscope with a wide-field contact lens (Mini Quad; Volk, Mentor, Ohio, USA) and 25 G chandelier by Alcon for illumination (Chandelier lighting system; Alcon) in 12 cases.⁵ In our previous pilot study, we included10 eyes that underwent scleral buckling under microscope using a 25 G chandelier by Alcon for illumination and a contact viewing system (HRX V it SSV lens) by Volk. ³

Hence, in this article, we report the surgical and long-term outcome of 82 cases undergoing chandelier assisted scleral buckling surgery using contact WAVs.

For endo-illumination, we used a 25‑gauge chandelier tip.Vitreous leak occurred in 12 eyes after removing the trocar. Thoughwith MIVS there are fewer chances of vitreous leak and infective endophthalmitis, we preferred to suture the sclerotomy whenever necessary.We did not encounter any case of endophthalmitis, as in the previous studies.

Chandelier tip theoretically may cause lens touch and retinal breakssecondary to the vitreous pull induced during globe rotation. In most studies includingours, none of these complications occurred. Imia et al study has reported a new break atthe site of the cannula in one eye and lens touch by the endoilluminator during cryoretinopexy inanother eye. We suggest removing the chandelier tip while suturing that requires extreme globe rotation to minimize these complications. In addition, the fiberoptic can come in the way of the needle holder, and hence we improvised by removing the fiberoptic and plugging the cannula for that part of the procedure. Once the suture is taken, we reintroduce the chandelier for visualization.

In our study, the primary success rate was 85.7% (15 out of 98 eyes) which wascomparable to previous reports. Failure in our cases was due to either non-closure of the breaks, formation of new breaks or progression of PVR.

We did not encounter any scleral perforation during indentation or subretinal bleedwhereas Aras reported 2 cases of each.⁴

In our series, despite a complete pre-operative examination, break was not visualized in 10 eyes. The causes were extremely bullous nature of the RD in 5 cases, breaks in the far periphery in 4 eyes and non-dilating pupil in 1 eye. These factors minimally affected visibility intra operatively using WAVs.

Overall, in our experience, chandelier assisted scleral buckling is safe, precise and comparable to the conventional method of scleral buckling using binocular indirect ophthalmoscope; while providing surgeon comfort and providing opportunity for fellows to observe the art of scleral buckling.

References:

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