American Academy of Ophthalmology Web Site: www.aao.org
New Findings from Ophthalmology, AJO and Archives
March’s American Journal of Ophthalmology:
January’s Archives of Ophthalmology:
Roundup of Other Journals:
In a 25-year population-based study of individuals with type 1 diabetes taking insulin, Klein et al. have found that relatively high incidence rates (29 percent) of macular edema and clinically significant macular edema (17 percent) are related to glycemia, systolic and diastolic blood pressure and nephropathy as manifested by gross proteinuria.
The researchers indicate a lower annualized incidence of macular edema and clinically significant macular edema in the last period of follow-up compared with earlier periods of follow-up—which may reflect recent improvement in care. Based on their findings, the researchers estimated that, of the 515,000 to 1.3 million Americans thought to have type 1 diabetes, between 149,000 and 377,000 will develop macular edema and 88,000 to 221,000 will develop clinically significant macular edema over the next 25 years. However, the decline in estimated annualized incidence between 2005 and 2006 suggests these numbers may be an overestimate.
The authors conclude that better glycemic and blood pressure control may be beneficial in reducing the incidence of macular edema.
Peripheral exudative hemorrhagic chorioretinopathy (PEHCR), a bilateral degenerative process of the eye, can be misinterpreted as an ocular tumor, particularly choroidal melanoma. Shields et al. conducted a noncomparative case series to evaluate the clinical features and outcomes of eyes with PEHCR that were simulating choroidal melanoma.
The study included 173 eyes of 146 patients who were referred for possible choroidal melanoma. Mean patient age was 80 years, and 145 patients were Caucasian. The clinical features differentiating PECHR from choroidal melanoma included the following: presence of retinal exudation, diffuse macular and peripheral retinal pigment epithelium atrophic findings; hypofluorescence of the lesion on fluorescein angiography; lack of intrinsic vascular pulsations and presence of a clot retraction cleft on ultrasonography; and lack of sentinel vessels on slit-lamp biomicroscopy.
In this study, the majority of PEHCR lesions spontaneously resolved, leaving retinal pigment epithelial atrophy, hyperplasia and fibrosis. The authors conclude that recognition of the PEHCR clinical features helps in differentiation from melanoma.
Results from the Atropine in the Treatment of Myopia Study by Tong et al. indicate that progression of low and moderate myopia can be slowed pharmacologically, with effects still persisting a year after treatment has been stopped.
In an initial two-year study, 400 children aged 6 to 12 received either atropine 1 percent or placebo eyedrops once nightly. Each child presented with a refractive error of spherical equivalent –1 D to –6 D and astigmatism of –1.5 D or less.
Researchers found an overall reduction in the progression of childhood myopia in the atropine-treated eyes compared with the placebo. This beneficial effect was maintained for one year following the cessation of treatment. In addition, the change in the axial length of the eyes over the entire three-year study, including the one year without treatment, was significantly less in treated eyes than in eyes not treated with atropine. Despite long-term atropine use, blurred near vision returned to what had been normal for the individual after the treatment was discontinued.
In a retrospective case series study, Roth et al. found that elevation of IOP in excess of 21 mmHg is common after intravitreal triamcinolone acetonide (IVTA) therapy.
In this series involving 929 eyes of 841 patients, 45.6 percent of eyes experienced an IOP measurement in excess of 21 mmHg within two years following IVTA therapy, and 28.9 percent experienced an IOP measurement of more than 25 mmHg. Study participants received up to seven IVTA injections throughout their treatment. IOP-lowering medications were required by many patients, but only three eyes required IOP-lowering surgery.
The authors conclude that the risk of steroid-induced ocular hypertension should not be an absolute contraindication to offering IVTA therapy.
Scott et al. have found that while center point thickness measured by ocular coherence tomography can serve as a useful tool for detecting and monitoring macular edema in retinal vein occlusion, it is not a reliable substitute for visual acuity measurements. These data are from the Standard Care Versus Corticosteroid for Retinal Vein Occlusion (SCORE) Study—two clinical trials investigating standard care vs. intravitreal triamcinolone acetonide injections for the treatment of vision loss associated with macular edema from central retinal vein occlusion and branch retinal vein occlusion.
This current report examines the relationships between visual acuity and morphological variables such as OCT-measured center point thickness in 655 participants. In patients with macular edema associated with central retinal vein occlusion and branch retinal vein occlusion, the correlation between OCT-measured center point thickness and visual acuity letter score was statistically significant but modest. These findings have implications in planning future clinical trials involving patients with retinal vein occlusion as well as the clinical management of these patients.
American Journal of Ophthalmology
In this prospective, nonrandomized clinical trial, 14 eyes of 14 patients were studied. Using light-adjustable lens technology, 13 eyes (93 percent) achieved ± 0.25 D of the target refraction at one day after lock-in, with 100 percent of the eyes achieving within 0.5 D of the targeted refractive adjustment at six months postoperative follow-up. All treated eyes showed no change in the manifest spherical refraction of greater than 0.25 D between one day post lock-in and three- and six-month postoperative visits.
The achieved refractive change remained stable after the adjustment and lock-in procedures. The mean rate of change was 0.006 D per month, which is six times more stable than that of refractive procedures. Using this technology, residual hyperopia errors in the range of 0.25 D to 2 D were successfully corrected with improvement in uncorrected visual acuity and without compromising BCVA.
Mitomycin is toxic to the anterior segment but is commonly used in many procedures. Bahar et al. evaluated the changes in endothelial cell counts in patients who underwent pterygium surgery with mitomycin C (MMC) 0.02 percent and compared them with patients undergoing pterygium excision without MMC.
In this study of 43 patients, 16 patients underwent pterygium surgery with conjunctival autograft and MMC for recurrent pterygium, and 27 patients underwent pterygium excision without MMC for primary pterygium removal. Endothelial images were acquired at the center of the cornea with a specular microscope before surgery and at one week, one month and three months following surgery.
Mean preoperative endothelial cell counts were 2,330 cells/mm2 in the control group and 2,486 cells/mm2 in the MMC group. One month after surgery, the MMC group showed an endothelial cell loss of 6 percent. This loss was not present in the control group. Three months after surgery, endothelial cell loss was reduced to 4 percent. In the MMC group, endothelial cell volume was increased (at one and three months), and the percentage of hexagonal cells was reduced (at one month but not at three months). Because of this deleterious effect on the corneal endothelium one month following surgery, judicious use of MMC is recommended.
Standard IOLs are usually calculated to provide distance correction. Leydolt et al. investigated pseudophakic patients with IOLs to assess the effect of training the patients’ near vision and motivating them toward a spectacle-independent outcome of their near-vision performance.
In this clinical trial, 80 eyes of 40 patients with standard cataract surgery were randomly assigned to a motivated or control group. In the motivated group, subjects were told that they were taking part in a special protocol to improve their near-reading ability after cataract surgery and were instructed not to use reading glasses for at least three months. They also received cycloplegic eyedrops for 10 days after surgery. Follow-up at three months included the following: BCVA, distance-corrected near visual acuity, best-corrected near visual acuity, assessment of the defocus curve, reading speed, and induced IOL shift assessed with partial coherence interferometry. A questionnaire evaluating patients’ postoperative satisfaction, independence from reading glasses and daily-life performance without glasses was carried out three months and one year postoperatively.
The authors did not detect any difference in reading ability or IOL shift between motivated and control patients. Although there was no improvement of ciliary body function in pseudophakic patients with this protocol, the motivated patients were less dependent on reading glasses, and their ability to perform activities without glasses was significantly better.
Detachment of the corneal graft is the most common postoperative complication of Descemet’s stripping endothelial keratoplasty (DSEK).
Lee et al. investigated a method of reducing rates of graft detachment in a case series of 83 consecutive patients undergoing DSEK for endothelial dystrophy. DSEK was performed in 103 eyes—83 donor grafts were not soaked and 20 donor grafts underwent presoaking in balanced salt solution. Of the 83 consecutive DSEK procedures carried out before presoaking the donor tissue, detachment occurred in 25 grafts. After presoaking, the detachment rate was reduced to zero.
Archives of Ophthalmology
Johnson et al. assessed whether optical coherence tomography can aid in differentiating optic disc edema (ODE) due to papilledema and other neuropathies from optic nerve head drusen (ONHD).
OCTs from 60 subjects were assessed qualitatively and quantitatively. Qualitative criteria for ODE included an elevated optic nerve head with smooth internal contour and subretinal hypo-reflective space (SHYPS) with a recumbent “lazy V” pattern. Criteria for ONHD included a “lumpy-bumpy” internal optic nerve contour and a rapid decline in SHYPS thickness. Quantitative comparisons in the study included retinal nerve fiber layer (RNFL) and SHYPS thicknesses measured at 0.75 mm, 1.5 mm and 2 mm from the optic disc center.
OCT differentiated ODE from ONHD qualitatively and quantitatively. Differences in mean RNFL thickness between ODE and ONH were significant superiorly, nasally, inferiorly and temporally. Differences in mean SHYPS thickness between ODE and ONHD were significant at all three radii (0.75 mm, 1.5 mm and 2 mm).
Chong et al. assessed the utility of spectral domain optical coherence tomography (SDOCT) in imaging children with nystagmus to better evaluate the spectrum of foveal architecture in pediatric albinism.
SDOCT imaging was performed on study subjects in three groups: subjects with ocular albinism (OA) or suspected OA; a subject with oculocutaneous albinism and Hermansky-Pudlak syndrome; and control subjects. Dense volumetric scans of each fovea were obtained with standard and handheld SDOCT devices.
Collected data were analyzed and scored for the presence and configuration of each retinal layer across the fovea. SDOCT images obtained from subjects in each of the noncontrol groups demonstrated a range of abnormalities, including presence of an abnormal, highly reflective band across the fovea, persistence of multiple inner retinal layers normally absent at the center of the fovea and loss of the normally thickened photoreceptor nuclear layer at the fovea. A secondary observation was that the optic nerve was elevated in multiple eyes of subjects with OA or suspected OA as well as the subject with oculocutaneous albinism and Hermansky-Pudlak syndrome.
The authors conclude that a spectrum of foveal morphological abnormalities is seen in subjects with OA or suspected OA. The OCT findings from this study are in contrast to those obtained from previous studies using time-domain OCT. The authors believe the current study may help clarify the morphology of foveal hypoplasia seen clinically.
Bressler et al. compared visual function in patients with neovascular age-related macular degeneration treated with ranibizumab or verteporfin photodynamic therapy (PDT).
At 12 months, patients treated with ranibizumab were more likely to im-prove substantially on the National Eye Institute Vision Function Questionnaire compared with patients treated with verteporfin PDT. In addition, it is the first study of treatment for neovascular AMD in which very large improvements were seen on patient-reported mental health outcomes: 50 to 60 percent of patients undergoing treatment with ranibizumab noted substantial improvements in this measure.
The improvements in visual function were noted as early as one month after treatment initiation in some patients and were maintained in most patients through two years of treatment.
Ophthalmology summaries are written by Lori Baker Schena and edited by John Kerrison, MD. American Journal of Ophthalmology summaries are edited by Thomas J. Liesegang, MD. Archives of Ophthalmology summaries are written by the lead authors.
Roundup of Other Journals
A long-term follow-up study of hereditary retinoblastoma patients by Marees et al. indicates that the overall risk of any second malignancies in hereditary retinoblastoma survivors is 20-fold higher than that of the general population. Using data from the Dutch retinoblastoma registry, the researchers analyzed risks of second malignancies in 668 patients diagnosed from 1945 to 2005 with either hereditary or nonhereditary disease based on the presence of family history, bilateral disease or a germline Rb1 mutation. The median follow-up for these individuals was 21.9 years.
The data showed increased risks of soft tissue sarcoma, osteosarcoma and melanoma in hereditary retinoblastoma patients—a finding the authors attributed to possible Rb1 germline mutation, radiotherapy treatment and the interaction between these factors. They also cited an excess risk of epithelial cancers such as bladder and lung cancer in middle-aged retinoblastoma survivors as a cause of concern. They recommend conducting lifelong follow-up studies to better determine the full extent of second malignancy risk.
Wu et al. examined the use of topical bevacizumab eyedrops to prevent an impending recurrence of pterygium from advancing to a true recurrence. The case involved a 53-year-old woman who, two months earlier, had undergone excision of a primary pterygium by bare sclera recision followed by application of mitomycin C. This patient also exhibited impending recurrent pterygium and received topical bevacizumab eyedrops (25 mg/ml) four times daily for three weeks.
This well-tolerated treatment approach significantly decreased limbal-conjunctival neovascularization—a key factor in blocking fibrovascular activity. After the patient stopped treatment, the limbal-conjunctival neovascularization continued to regress. Six months later, the authors did not detect recurrent pterygium or adverse ocular effects. In addition, the patient’s symptoms cleared up with no ocular irritation or adverse systemic effects.
Do et al. offer a quantitative foundation for understanding intrinsically photosensitive retinal gangion cells (ipRGCs), including basic parameters concerning their absolute sensitivity.
IpRGCs—which express the pigment melanopsin and depolarize to light—are less photosensitive than rods and cones. The researchers explain that these cells are involved in non-image-forming visual functions such as pupillary light reflex and circadian photoentrainment. The authors also discuss the parameters governing the intrinsic light responses of ipRGCs and the associated spike generation. The membrane density of melanopsin is 104-fold lower than that of rod and cone pigments, resulting in a very low photon catch and a phototransducing role only in relatively bright light.
However, each captured photon does elicit a large and extremely prolonged response, producing a unique shape compared with other known photoreceptors. And, similar to rods, ipRGCs can signal single-photon absorption.
Roundup of Other Journals is written by Lori Baker Schena and edited by Deepak P. Edward, MD.