Dr. Shrikant Prasad, P19187, Dr. Alok Sen, Dr. Ashish Mitra
Author : Dr Shrikant Prasad
Co author: Dr Alok Sen, Dr Ashish Mitra
Aim:To compare the outcomes of SB using a WAVS with that of SB using conventional indirect ophthalmoscopy for rhegmatogenous retinal detachment
Methods:The clinical records of 31 eyes(31 pts) with RRD primarily treated between Jun 2014 and Jan 2016 were retrospectively analysed.SB was performed using WAVS with an endoilluminator in 15 eyes and indirect ophthalmoscopy in 16 eyes
Results:The preoperative findings, intraoperative findings, postoperative complications and success rate of retinal reattachment were evaluated.There were no significant differences between groups, and similar surgical outcomeswere achieved with the WAVS and conventional procedures.However,compared with the conventional procedure,the WAVS procedure resulted in fewer intraoperative corneal epithelial disorders (p = 0.049) and decreased the surgical duration of SB(p = 0.02)
Conclusion:Chandelier assisted illuminationwithWAVS may be suggested as an effective alternative procedure for SB with favourable outcomes
Introduction:
Although recent progress in pars plana vitrectomy (PPV) has expanded its application to rhegmatogenousretinal detachment, scleral buckling remains a valuable surgical procedure and is the first-line treatmentfor particular cases, such as those involving rhegmatogenous retinal detachment caused by retinalholes in the lattice in young patients. Although an attempt to improve the method of scleral buckling bythe substitution of indirect ophthalmoscopy with a noncontact wide-angle viewing system (WAVS) was
recently made(1–3), no study has compared the surgical outcomes of the two procedures.
Scleral buckling is a well-established procedure for treating rhegmatogenous retinal detachment.However, conventional scleral buckling using indirect ophthalmoscopy has several limitations, whichsurgeons endeavour to resolve through further modifications. In the conventional procedure, extensiveindentation for cryopexy may cause inflammation; moreover, the surgical field cannot be shared duringsurgery or recorded on video, thus compromising the support provided by surgical assistants andco-medical staff as well as resident education. The aforementioned issues were mostly resolved throughthe use of a noncontact WAVS during surgery, which requires lesser indentation for observing the breaksand effects of cryopexy. Furthermore, during indentation, the surgical field can be visualized through themicroscope and/or can be recorded, making it convenient for patients, surgeons, assistants, and residentsin need of training1–3.
Although the advantages of WAVS-assisted scleral buckling are well accepted, an objective comparison of its outcomes with those of conventional scleral buckling using indirect ophthalmoscopy has not
been performed. Therefore, in this study, we compared the two procedures with regard to the success rate of retinal reattachment, intraoperative findings, and postoperative complications in order to elucidate the effectiveness of WAVS-assisted scleral buckling and establish its use.
Results
Patient demographics.
In this study, we included 16 eyes of 16patients (10 men and 6 women; average age= 51.5 years; range 19–60 years) who underwent scleral buckling with conventional indirect ophthalmoscopy and 15 eyes of 15 patients (10 men and 5 women; average age= 27.5 years;
Range 13–67 years) who underwent scleral buckling with WAVS. The surgical procedure was selected depending on the period; the conventional procedure was selected in the initial period and WAVS was selected in the later period. All procedures other than the method of fundus visualization were identical in both groups, with the exception of the use of viscoelastic material in the WAVS group.
As a standard, viscoelastic material is generally used with WAVS during PPV4. The average postoperative follow-up period was 12 months, ranging from 6 to 18 months.
There were no significant differences between the two groups with regard to patient age (p = 0.32), gender (p = 0.29), the localization of retinal breaks, the extent of retinal detachment (p = 0.35), the preoperative best-corrected visual acuity (BCVA; logMAR, p = 0.17), and the spherical equivalent refractive error (p = 0.05).
Surgical procedure: Local anesthesia was induced by the retrobulbar injection of 2% lidocaine. The sclera was exposed with a perilimbal conjunctival incision. Once the extraocular muscles were hooked at the insertion site, tractional sutures were placed with 2-0 black silk.
Then, during scleral buckling with the noncontact WAVS, a scleral incision was placed with a 25Gtrocar cannula at a distance of 4 mm from the corneal limbus for the insertion of an endoilluminator
(ChandelierLighting System,Alcon, Fort Worth, Texas, USA). The position of the sclerotomy wasselected according to the localization of the break. The sclerotomy was created in the samequadrant as the break to avoid additional invasion of the conjunctiva. A plug was inserted into the trocarwhen the endoilluminator was removed from the trocar without a check valve. A viscoelastic material (Aurovisc,Auro lab, Madurai,India) was placed on the corneal surface during surgery. Fundus observation was performed through the noncontact WAVS (Resight; Carl Zeiss Meditec AG,Jena, Germany or BIOM; Oculus, Germany) using the endoilluminator. The localization of the retinalbreaks was identified and cryopexy was performed through WAVS. After the endoilluminatorwas removed, a silicone tire (#276MIRA, USA) with a silicone band (#240 MIRA, USA) was fixed to the sclera with mattresssutures using 5-0 polyester (Aurolab, madurai, India). Then, the endoilluminator was reinsertedto confirm the adequacy of the position and height of the buckle. Subretinal fluid drainage wasperformed using a 26 G needle externally. Finally, after checking the fundusthrough WAVS, the 25G cannula was removed, followed by cotton swab compression. The conjunctiva
was closed with 6-0 silk vicrylsutures.During conventional scleral buckling using indirect ophthalmoscopy, fundus observation was performedthrough an indirect ophthalmoscope without a cannula to mark the breaks and perform cryopexy.
The silicone materials were placed and subretinal fluid was drained using the same methods usedin the WAVS group. The position and height of the buckle were confirmed by indirect ophthalmoscopy.
Physiological saline irrigation was employed during surgery to prevent the corneal surface from drying.
Statisticalanalysis:All values are expressed as mean±standard deviation. The results were comparedusing the Mann–Whitney U test. All statistical analyses were performed using SPSS (version 16.0, trial version). A p-value of <0.05 was considered statistically significant.
Intra- and post -operative findings: No significant difference was observed in the rate of retinal reattachment after the first surgery Furthermore, no significant differences were observed in the postoperative BCVA (p = 0.218) between groups, and the postoperative spherical equivalent refractive error was comparable with the preoperative error (p = 0.39). Although there was no significant difference in the overall surgical duration between the WAVS and conventional groups (p = 0.07), the surgical duration was significantly shorter in the WAVS group than in the conventional group when the analysis was limited to patients who underwent
segmental buckling (p = 0.02). An intraoperative complication, namely retinal herniation at the time of external subretinal fluid
drainage occurred in one eye in the conventional group. A significant difference was observed in the number of eyes that underwent corneal epithelial peeling due to intraoperative epithelial edema between
the WAVS (n = 0) and conventional groups (n = 5; p = 0.043).
There was a trend for a higher incidence of postoperative corneal epithelial disorders in the conventional group (n = 5) compared with that in the WAVS group (n = 0), although the difference is
significant (p = 0.043). Postoperative complications included one case of macular pucker in the WAVS group (p = 0.512) and one case each of cataract formation (p = 0.4 and macular edema (p = 0.301) in the conventional group.
Discussion
In this study, we compared the rate of retinal reattachment and postoperative BCVA between patients treated by scleral buckling using WAVS and those treated by scleral buckling using conventional indirect ophthalmoscopy. We found no significant differences between the two groups with regard to both parameters.
In addition, we found that the intraoperative corneal condition was better and the surgical duration for segmental buckling was shorter in patients treated by WAVS-assisted scleral buckling. We found no
surgical complications related to scleral incision and intraocular insertion of the endoilluminator in this study, although such a concern was theoretically raised.
To date, several studies have described the technique for scleral buckling using WAVS and its surgical outcomes. These reports recommend the use of WAVS in cases of undetected retinal breaks1 and show that WAVS generally has favorable surgical outcomes 2, 3, 5. However, no study thus far has directly compared WAVS with the conventional method for scleral buckling, and to our knowledge, the present case series represents the first comparative study of these procedures based on clinical chart reviews.
The findings of this study showed that patients treated with noncontact WAVS had significantly better ocular surface conditions during surgery. This was probably because the retinal breaks could be easily observed with less scleral indentation because of the wide surgical view through the noncontact WAVS, thus inducing a smaller increase in the intraocular pressure and placing less stress on the cornea. We placed a viscoelastic material on the cornea when using the noncontact WAVS, which is commonplace during WAVS-assisted PPV4; this step may also have contributed to the maintenance of a better corneal condition. The viscoelastic material was not used in the conventional group, because it is not used in the conventional buckling procedure.
Contact lenses placed during PPV may also avoid corneal drying, but they have a narrow surgical view that can be slightly disadvantageous; however, contact lenses were not included for analysis in this study. Because noncontact WAVS provides a good surgical view in cases of corneal opacity and small pupils4, WAVS can prove advantageous for the treatment of rhegmatogenous retinal detachment accompanied by such complications.
The shorter surgical duration with WAVS-assisted segmental buckling may be attributed to the wide surgical field, which allows the surgeon to mark the breaks easily for cryopexy. The surgical duration for WAVS-assisted encircling buckling showed a decreasing trend, although there were no significant differences, probably because the surgical duration included the time spent on procedures other than marking, cryopexy, and final check of the fundus. There was no limitation in scleral depression because a perilimbal conjunctival incision was made. We had examined the fundus carefully to identify the breaks before surgery; therefore, the cannula was appropriately placed according to the rule and did not interfere with scleral indentation. The retina near the incision point of the cannula was lightened by tilting the latter. At this time, we had to carefully avoid touching the lens. An endoilluminator with a
smaller gauge, e.g., 25G, may be easier to light around the incision site. The scleral buckling procedure may sometimes injure the neck and back of surgeons because of the posture required to perform this procedure. The use of WAVS enables surgeons to sit down and maintain a comfortable posture during the entire procedure6. This aspect, however, was not objectively evaluated in the current study.
A few disadvantages of WAVS are the costs involved and facilities required. Trocar cannulas and endoilluminators required for WAVS are disposable instruments. Furthermore, in three patient (incidence,
20%) in the WAVS group, macular pucker developed as a postoperative complication and necessitated an additional surgery. Nevertheless, the incidence of this postoperative complication is similar to that reported with the conventional procedure (4%–8.5%) 7–9.
This study has some limitations. The sample size was relatively small, while the follow-up period was relatively short. A study with a larger sample size or a prospective study is required to precisely compare
the effects of these surgical methods in the future. Theoretical surgical complications related to scleral incision and intraocular insertion of the endoilluminator include vitreous wick from the scleral wound,
endophthalmitis, lens damage, and light toxicity1. Although these complications did not occur in this study, a longer follow-up of a larger population should be performed before a conclusion regarding the use of WAVS is reached.
Conclusion : In the current study, the WAVS and conventional procedures showed similar rates of retinal reattachment, postoperative BCVA, and retinal complications. Moreover, intraoperative corneal epithelial disorders were less frequent. Furthermore, this procedure may be more conducive to resident training.
Although further studies using a larger study group and longer follow-up period are required, WAVS may be considered an alternative standard procedure for scleral buckling in the future
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