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Research Digest

New & Noteworthy Journal Articles

Compiled by Andrew E. Mathis, PhD, Medical Editor

► RNFL thickness without glaucoma. There’s a high rate of both glaucoma and sickle cell disease among African Americans, but what about retinal nerve fiber layer thickness in black patients with sickle cell disease but without glaucoma?

To determine whether a relationship existed, ophthalmologists at the University of Illinois at Chicago used spectral-domain OCT to examine RNFL thickness in 151 eyes of 88 patients with three types of sickle cell disease, as well as 30 controls.

They found thinner peripapillary RNFL thickness in the nasal and superotemporal sectors of eyes of patients with sickle cell disease. In addition, in a subgroup with extreme macular thinning, six of seven sectors had a thinner RNFL.

The authors concluded that African-American patients with sickle cell disease may require different peripapillary RNFL thickness thresholds when being screened for glaucoma.

Chow CC, Shah RJ, Lim JI, Chau FY, Hallak JA, Vajaranant TS. Peripapillary retinal nerve fiber layer thickness in sickle-cell hemoglobinopathies using spectral-domain optical coherence tomography. Am J Ophthalmol. 2013;155:456-464.e2.

► More on glaucoma. On a related topic, newly published data from the African Descent and Glaucoma Evaluation Study, conducted at centers in New York, San Diego and Birmingham, Ala., indicated that the effect of race on ocular structural asymmetry might be overestimated.

Five hundred nineteen healthy patients from this study and from the Diagnostic Innovations in Glaucoma Study, both black and white with mean age in the mid-40s, underwent retinal tomography, standard automated perimetry and GDx variable corneal compensation testing.

While subjects of African descent initially showed higher median asymmetry in cup size and rim volume, multivariate analysis eliminated a significant relationship. Most other measurements were comparable between racial groups.

The authors suggested little need exists for race-specific databases in glaucoma screening, disagreeing with some conventional wisdom in this area.

Moore GH, Bowd C, Medeiros FA, et al. African descent and glaucoma evaluation study: asymmetry of structural measures in normal participants. J Glaucoma. 2013;22:65-72.

► Stem cell transplant rejection. Rejection can be an unfortunate outcome of ocular surface stem cell transplantation (OSST). To provide information on the incidence, characteristics and outcomes in cases of OSST rejection, doctors collaborating between the United States and Australia undertook a chart review of 222 eyes of 158 patients submitted to OSST.

Eyes with aniridia, chemical or thermal injuries, Stevens-Johnson syndrome, and other diseases were treated with OSST, in most cases with keratolimbal allografts. Twenty-six eyes experienced low-grade rejection at a mean of 26.2 months after OSST, and only roughly half the eyes experiencing rejection achieved a stable ocular surface at final follow-up.

Younger patients, those receiving keratolimbal allografts alone and patients not compliant with taking immunosuppressive medication were more likely to experience rejection.

Ang AY, Chan CC, Biber JM, Holland EJ. Ocular surface stem cell transplantation rejection: incidence, characteristics, and outcomes. Cornea. 2013;32:229-236.

► BAK-free glaucoma drops. The T2345 Study Group in Europe has been comparing the safety and efficacy of benzalkonium chloride (BAK)-preserved latanoprost eyedrops vs. preservative-free drops in patients with primary open-angle glaucoma or ocular hypertension. In a study designed to yield level 1 evidence, 402 patients who previously received BAK-preserved drops were randomized to receive either BAK-preserved or preservative-free drops. Mean IOP, measured over seven months, lessened by only 2% in the preservative-free group. Moderate to severe hyperemia was significantly less frequent in the group not receiving BAK. That group also had a lower subjective ocular symptom score, proving the non-inferiority of BAK-free drops to drops containing BAK. The authors recommended the use of BAK-free drops whenever possible, particular in the setting of comorbid ocular surface disease.

Rouland JF, Traverso CE, Stalmans I, et al; T2345 Study Group. Efficacy and safety of preservative-free latanoprost eyedrops, compared with BAK-preserved latanoprost in patients with ocular hypertension or glaucoma. Br J Ophthalmol. 2013;97:196-200.

► Angiogenesis and ROP. Researchers collaborating between the United States and Mexico have published follow-up data of up to five years on infants with retinopathy of prematurity treated with anti-angiogenesis drugs.

In this prospective study, 18 eyes of 13 babies were first divided into three groups: a group unresponsive to traditional treatment; a group in whom conventional treatment could not be given because of insufficient retinal visualization; and a newly diagnosed group. All patients were given Avastin (bevacizumab, Genentech), and all of them responded with regression of neovascularization.

One patient who relapsed was retreated. Twelve of the 18 eyes developed myopia. The results suggest that anti-VEGF drugs could constitute an effective therapy for ROP. Given the length of the follow-up in this study, it also contributes to the growing body of evidence suggesting that intravitreal Avastin is safe in the longer term. OM

Martínez-Castellanos MA, Schwartz S, Hernández-Rojas ML, et al. Long-term effect of antiangiogenic therapy for retinopathy of prematurity: up to 5 years of follow-up. Retina. 2013;33:329-338.