CASE REPORT LATE ONSET CAPSULAR BLOCK SYNDROME AFTER MANUAL SMALL INCISION CATARACT SURGERY: A CASE REPORT

Capsular block syndrome is a rare complication of cataract surgery seen with continuous curvilin - ear capsulorrhexis and in-the-bag placement of posterior chamber intraocular lens. We report an uncommon case of late postoperative fibrotic capsular block syndrome with posterior capsular opacification in an adult Nepali patient after uneventful manual small incision cataract surgery which was successfully treated with Nd: YAG laser capsulotomy without any complications.


INTRODUCTION
Capsular block syndrome (CBS) is an uncommon complication seen after cataract surgery with continuous curvilinear capsulorhexis (CCC) and in-the-bag placement of a posterior chamber intraocular lens (PCIOL). Patient with this syndrome often have a myopic shift, anterior displacement of the iris lens diaphragm, shallow anterior chamber, raised intraocular pressure. It is characterized by adherence of the anterior capsule to the intraocular lens and blockage of the contents within the capsular bag. 1 Miyake et al. 2 has classified capsular block syndrome into intraoperative, early post-operative and late post-operative according to the time of onset. Kim and Shin 3 classified postoperative CBS into non-cellular, inflammatory and fibrotic according to the clinical characteristic and pathogenetic origin. We report a case of late post-operative capsular block syndrome with PCO in an adult Nepali male presenting three years after the uneventful manual small incision cataract surgery (SICS).

CASE REPORT
A 66-year-old Nepali male with no notable medical history presented with gradual blurring of vision in right eye for last six months. His unaided visual acuity was 3/60 in the right eye and 6/60 in the left eye. The vision in the right eye was not improving with refraction while the left eye improved to 6/18 with -2.5 DS/-0.50 DC x 100° correction. The intraocular pressure on goldmann applanation tonometry was 12 mmHg in both eyes. He had undergone right eye uneventful manual small incision cataract surgery (SICS) and single piece polymethylmethacrylate (PMMA) posterior chamber intraocular lens (PCIOL) implantation three years back with good postoperative gain of vision. Slit-lamp examination under mydriasis showed clear cornea, quiet anterior chamber with normal anterior chamber depth, regular CCC with fibrosis between anterior capsule margin and optic of PCIOL, elschnig's pearl-type posterior capsular opacification (PCO) and collection of milky-white fluid between the posterior surface of intraocular lens (IOL) and posterior capsule in the right eye ( Figure 1& 2). Left eye showed nuclear sclerosis of grade II. Fundus examinations were normal in both eyes.
The diagnosis of right eye late onset capsular block syndrome with PCO was made and neodymium-yttrium-aluminumgarnet (Nd:YAG) capsulotomy to the posterior capsule was performed in the right eye. The milky-fluid dispersed into the vitreous cavity leading to disappearance of PCO and capsular   After the procedure, there was immediate improvement in visual acuity in the right eye to 6/9 with -0.50 DS/ -0.50 DC x 100°correction. The patient was prescribed topical prednisolone 1% four-times-a-day and timolol 0.5% twice daily for a week. The patient had uneventful follow up for last three months.

DISCUSSION
Capsular block syndrome is a rare complication of cataract surgery that occurs with posterior chamber in-the-bag IOL implantation and CCC. It was first described by Davison 4 in 1990 as an early postoperative complication. Since then several case studies of postoperative CBS have been reported. Miyake et al. 2 classified capsular block syndrome into intraoperative, early post-operative (occurring 1-15 days after surgery) and late post-operative (occurring an average of 3.8 years after surgery). Kim and Shin 3 divided postoperative CBS into three types: non cellular, inflammatory, and fibrotic. Non cellular CBS occurs within a day after surgery and is caused by an ophthalmic visco-surgical device. Inflammatory CBS develops several days after surgery and is caused by severe inflammatory cellular reaction. Fibrotic CBS occurs in late postoperative period and is characterized by fibrosis over the entire circumference of the anterior capsule opening and PCO. 3 In our case, milky-white fluid accumulation was seen between IOL and posterior capsule along with the fibrosis in the entire anterior capsule opening and elschnig's pearl-type PCO suggesting late postoperative fibrotic CBS with PCO.
CBS is clinically characterized by capsular bag distension, anterior displacement of the iris lens diaphragm, shallow anterior chamber and unexpected myopic shift. Myopic shift is usually seen in intraoperative and early postoperative CBS due to forward displacement of the IOL 1 while in late postoperative CBS myopic shift, hyperopic shift or no change in refraction have been reported. 5,6 Although CBS is a clinical diagnosis, a definitive diagnosis and better characterization of anatomical structures can be achieved by using diagnostic aids such as anterior segment ultrasound biomicroscopy (UBM), optical coherence tomography (OCT) and Scheimpflug-based photography (Pentacam). 7 Late postoperative CBS are usually underdiagnosed due to its asymptomatic nature and can be mistaken for PCO. The PCO and late postoperative CBS are treated by creating an opening in the posterior capsule with the Nd:YAGlaser. 8,9 Other potential management options for CBS include observation, use of antiinflammatory medications in presence of inflammation 3 , slit lamp needle revision 10 , surgical aspiration of fluid 11 or pars plana vitrectomy with surgical removal of posterior capsule. 12 Nd: YAG laser capsulotomy can fail in some cases due to inability to accurately focus the laser beam on the posterior capsule because of the opacity of the contents in the distended capsular bag and the surgical drainage of the entrapped fluid need to be performed in such case. 11 However, we did not encounter such difficulty and Nd: YAG capsulotomy was successfully done. After Nd: YAG capsulotomy the fluid accumulated behind the IOL and posterior capsule gets dispersed into vitreous cavity or the anterior chamber. The accumulated fluid behind the IOL in CBS have been reported to contain Propionibacterium acne, 12 so the access of the fluid into the vitreous cavity might cause a delayed endophthalmitis. In our case the dispersed milky-white fluid was cleared from the vitreous cavity without any consequences like inflammation or raised intraocular pressure after Nd: YAG capsulotomy.