Eyeworld

EW RESIDENTS 58 July 2015 by Marius Tijunelis, MD, MBA, and the residents of the Kellogg Eye Center, University of Michigan suspect, PAC, and PAC glaucoma (PACG). 1 A PAC suspect is a patient with the potential of develop- ing peripheral iris and trabecular meshwork contact. A PAC patient is defined as having an occludable drainage angle and physical signs of peripheral anterior synechiae, elevated intraocular pressure (IOP), iris whorling, glaukomflecken, or excessive pigment deposition on the trabecular meshwork. Final- ly, a PACG patient is defined as showing signs of optic nerve injury or nerve fiber layer infarcts. Us- ing such a classification system, a recent meta-analysis projected that the worldwide number of people with glaucoma between 40 and 80 years of age will increase from 64.3 million in 2013 to 111.8 million in A controversial indication for clear lens extraction is chronic angle closure. A sizable clinical study of this procedure appears in this month's JCRS and is reviewed by the Michigan residents. –David F. Chang, MD, EyeWorld journal club editor T he epidemiology of an- gle closure glaucoma has been clarified by dividing primary angle closure (PAC) into 3 classifications: PAC 2040. 2 The pooled global prevalence of primary open angle glaucoma (POAG) is estimated to be 3.05% and of primary angle closure glau- coma (PACG) to be 0.69%. Tham et al estimated 23.4 million PACG cases, which is comparable to prior estimates of 21 million cases using PACG prevalence estimates from European epidemiology studies. 3 The 5-year risk of progressing from PAC to PACG is reported between 11.1% and 28.5%. 4,5 The standard approach for a patient with PAC begins with a laser peripheral iridotomy (LPI) that has been shown to be effective in open- ing the angle in 73.4% of patients with chronic PACG. 6 If the IOP re- mains elevated, ocular hypotensive medications are started. If the IOP remains elevated on ocular hypoten- sive medications and/or the patient develops glaucoma with visual field deficits, then surgical intervention with trabeculectomy is offered. However, recently the role of clear lens extraction (CLE) in the preven- tion of PACG has stimulated a great deal of interest. 7,8 In the "Clinical outcome of clear lens extraction in primary angle closure" published in the July issue of the Journal of Cataract & Refractive Surgery, Dada and col- leagues report the effect of clear lens phacoemulsification and implan- tation of a foldable single-piece hydrophobic acrylic intraocular lens (IOL) in the capsular bag on patients with PAC. This pilot, non-random- ized, prospective, single surgeon study of 44 eyes in 44 consecutive PAC patients was performed over 2.5 years at a tertiary care center at the Dr. Rajendra Prasad Centre for Ophthalmic Sciences at the All India Institute of Medical Sciences, New Delhi, India. Inclusion criteria consisted of PAC cases with a BCVA of >20/20, who were >50 years old, phakic, and had at least 3 occludable quadrants by gonioscopy. In addition, each patient had a peripheral iridotomy that was performed at least 8 weeks prior to measuring an elevated IOP >25 mm Hg despite using hypo- tensive medications. Patients were excluded from the study if they were PAC suspects, had PACG, or were monocular. The preoperative work-up con- sisted of visual acuity, applanation tonometry, slit lamp exam with 90 D optic nerve head evaluation, gonios- copy, A-mode contact ultrasonogra- phy, keratometry, humphrey visual fields, and anterior-segment optic computed tomography (AS-OCT). The AS-OCT was used to calculate various angle parameters: anteri- or chamber depth, lens thickness, angle opening distance, trabecular iris angle, trabecular iris surface area and lens vault. The postop course consisted of 4 weeks of steroids/anti- biotics, while all ocular hypotensive medications were discontinued. Oc- ular hypotensive medications were restarted only if the IOP >21. Over the next 12 months, the IOP, visual acuity (distance and near), and AS- OCT parameters were recorded on regularly scheduled intervals. The primary outcome measure was the mean IOP change between preoperative and postoperative IOPs. Two secondary outcome measures were the change in angle parameters and the change in ocular hypo- tensive medications. Using these outcome measures absolute success was defined as an IOP <18 mm Hg without any ocular hypotensive medications and a qualified success if the IOP was <18 mm Hg with ocu- lar hypotensive medications. The 12-month outcome demon- strated that clear lens extraction reduced the IOP by a mean of 14.29 +/–1.83 mm Hg from a preopera- tive IOP of 27.1 +/–1.55 mm Hg to postoperative IOP of 13.2 +/–1.12 mm Hg (p value of 0.0001). The secondary outcomes noted statisti- cally significant angle widening and increase in central chamber depth. Also, 38 of 44 patients discontinued ocular hypotensive medications and 6 of 44 patients continued only one ocular hypotensive medication. A decline in uncorrected near visual acuity was consistent with replacing a crystalline lens with a monofocal IOL and loss of accommodation; however, it was not clear why after 12 months, the best corrected near visual acuity remained at only J6. The strengths of this study include a prospective study design with well-defined inclusion criteria and 12-month follow-up data that suggests that clear lens extraction is a viable alternative for PAC patients Review of "Clinical outcome of clear lens extraction in primary angle closure" Clinical outcome of clear lens extraction in primary angle closure Tanuj Dada, MD, Anubha Rathi, MD, Dewang Angmo, MD, Tushar Agarwal, MD, M. Vanathi, MD, Sudarshan K. Khokhar, MD, Rasik B. Vajpayee, MS, FRCS(Ed) J Cataract Refract Surg (July) 2015;41. Article in press Purpose: To evaluate the effect of clear lens extraction on intraocular pressure (IOP) and anterior chamber angle parameters in patients with primary angle closure (PAC) with raised IOP post laser peripheral iridotomy (LPI). Setting: Dr. RP Centre for Ophthalmic Sciences, AIIMS, New Delhi, India Design: Prospective non-randomized clinical trial Methods: Forty-four eyes of 44 phakic patients with PAC and BCVA≥20/20 with IOP >25 mm Hg beyond 8 weeks post LPI were included. Workup comprised of applanation tonometry, biometry and anterior segment optical coherence tomography (angle opening distance at 500 µ [AOD 500], trabecular iris angle [TIA]). All eyes underwent phacoemulsification clear lens extraction with IOL implantation. The criterion for absolute success was IOP <18 mm Hg without ocular hypotensive medications, and follow-up examination was performed at 3, 6, and 12 months. Results: There were 24 females and 20 males with mean age of 57.2±4.2 years. Mean preoperative IOP of 27.1±1.55 mm Hg reduced to 13.2±1.12 mm Hg at 12 months (p<0.0001). Significant widening of the angle was noted at 12 months with an increase as compared to baseline values in AOD500 at 0 degrees (0.104±0.015 mm vs. 0.31±0.013 mm); AOD500 at 180 degrees (0.202±0.008 mm vs. 0.412±0.012 mm); TIA at 0 degrees (9.3±3.2 degrees vs. 32.7±5.6 degrees); TIA at 180 degrees (9.12±3.2 degrees vs. 31.7±5.6 degrees); all p<0.0001. In multivariate analysis, preoperative IOP was the strongest determinant of the change in IOP (p<0.0001, R 2 =0.69). Absolute success was achieved in 38 eyes (86.3%) at 12 months. Conclusions: Clear lens extraction is associated with a significant reduction in IOP, widening of the anterior chamber angle and a reduced need for ocular hypotensive medications in PAC eyes with persistently raised IOP post LPI. Shahzad I. Mian, MD, residency program director, University of Michigan EyeWorld journal club

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