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Sclerostomy with phaco reduces complication rates in nanophthalmic eyes
Surgeon explains how the combined procedure can be safer and easier in these difficult cases.
Performing a simultaneous prophylactic sclerostomy with phacoemulsification reduces complication rates in nanophthalmic eyes with cataract, according to a study carried out at Aravind Eye Hospital, Madurai, India.
In nanophthalmic eyes, which have a very short anterior segment and a thick sclera, cataract surgery is a challenge. The sudden decrease in pressure and the pressure differential between the anterior and posterior segments might lead to positive vitreous pressure. Complications such as iritis, uveal effusion, corneal decompensation, retinal detachment, zonular rupture, cystoid macular edema and vitreous hemorrhage are frequent. Postoperatively, the risk for IOP rise and glaucoma is high.
“In our experience, we have seen that performing scleral window surgery by decompressing the eye posteriorly through a small scleral window helps reduce complications,” Sharmila Rajendrababu, MD, told Ocular Surgery News.
Aravind Eye Hospital is the only large tertiary eye care center in the south of India and a referral center that serves other parts of the country. This is why, although nanophthalmos is a rare condition, a high number of these patients are seen there.
“In our study, we included 60 patients aged between 48 and 68 years with nanophthalmic eyes and cataract, and randomly assigned them to undergo surgery with or without sclerostomy. In all the eyes I performed peripheral iridotomy 2 weeks prior to surgery,” Rajendrababu said.
Safer procedure, fewer complications
“We are in the developing world, and besides patients who present relatively early with cataract grade 1 or 2, we see a lot of denser cataracts of grade 4+ nuclear sclerosis. The choice of surgery depends on the opacity of the nucleus and the depth of the anterior chamber. We perform phacoemulsification whenever possible, but there are a few cases in which we do small-incision cataract surgery as well,” Rajendrababu said.
In the patients who received the combined procedure, a retina surgeon performed a single prophylactic sclerostomy in the inferotemporal quadrant before cataract surgery. A conjunctival peritomy was performed, the bleeding vessels were cauterized, and the inferior and lateral rectus muscles were brindled, exposing the sclera. A 4 mm × 4 mm superficial scleral flap was created, and a 2 mm × 2 mm deeper scleral block was excised to create a window. The edges of the window were then cauterized to prevent closure and allow a slow drainage of fluid.
“When the sclerostomy was done, there was a small change in anterior chamber depth and the eye became soft. We could not objectively measure it or document it, but the difference was clearly visible. The eye was softer, the space was larger, and everything was easier than in the other group,” Rajendrababu said.
Intraoperative complications were significantly fewer in the sclerostomy group than in the group without sclerostomy. There was one case of iridodialysis, three cases of posterior capsule tear and one case of zonular dialysis in the control group as compared with only one case of Descemet’s membrane stripping in the sclerostomy group. The greatest difference was in the rate of postoperative complications.
“There were four cases of choroidal effusion in the control group but none in the sclerostomy group. Something remarkable, it really makes things easier,” Rajendrababu said.
Although sclerostomy performed at the time of cataract surgery is not a new technique, this was the first randomized study to demonstrate its impact on complications.
“We now feel very comfortable performing cataract surgery in nanophthalmic eyes; even dense, difficult cataracts are no longer a nightmare,” Rajendrababu said.
Recommendations and future projects
Rajendrababu recommended performing a detailed preoperative assessment in nanophthalmic eyes as it is often missed in a routine clinical examination.
“Carefully measure the axial length, corneal thickness, lens thickness and anterior chamber depth. Use ultrasonography to evaluate scleral thickness, and then look at the grading of the cataract to plan surgery accordingly. If there is any kind of uveal effusion that you pick up by ultrasound, first perform a scleral window surgery and later plan a cataract surgery subsequently,” Rajendrababu said.
Most of these eyes have shallow chambers and are more prone to angle closure. To prevent it, Rajendrababu routinely performs laser peripheral iridotomy in these patients. She also recommended administering intravenous mannitol 1 hour before the surgery to reduce the positive vitreous pressure and to provide better control of IOP.
“Make sure the retinal surgeon is always there, and always do sclerostomy before cataract surgery, especially in eyes with very short axial length,” she said.
She also recommended performing phacoemulsification with a soft-shell technique, using a very high molecular weight, cohesive viscoelastic to deepen the anterior chamber and to protect the endothelium. The use of an anterior chamber maintainer might enhance safety and comfort and may be worth investigating, she said.
“We have further projects in the pipeline. One of them is to use customized lenses for these patients. Most of them require more than 50 D of correction, but the available power is only up to 40 D. We can think of providing suitable correction by single high refractive index lenses or by piggyback. We are also working with a company to measure objectively the change in anterior chamber depth after sclerostomy with a microscope-mounted OCT. We are also looking into the genetic aspects of nanophthalmos by collecting information in the families of patients. Finally, we are doing histopathological examinations to find potential biomarkers within the sclera,” Rajendrababu said. – by Michela Cimberle
- For more information:
- Sharmila Rajendrababu, MD, can be reached at Aravind Eye Hospital, 1 Anna Nagar, Madurai, Tamil Nadu, 625020 India; email: shamsreddy@yahoo.com.
Disclosure: Rajendrababu reports no relevant financial disclosures.