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Journal Highlights
New Findings from Ophthalmology, AJO and Archives
 
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Ophthalmology:

American Journal of Ophthalmology:

Archives of Ophthalmology:

Roundup of Other Journals:

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Ophthalmology

Cataract Surgery Database Analyzed With Focus on Endophthalmitis
Ophthalmology
Published online Feb. 1, 2012

Keay et al. analyzed data from more than 3 million Medicare beneficiary claims billed in 2003 and 2004 to estimate the annual incidence of endophthalmitis. They found an average of 1.22 cases per 1,000 surgeries. These rates of endophthalmitis were lower than previous annual U.S. estimates but higher than studies conducted in Sweden. The investigators also found that half of states had an adjusted rate of between 1.43 and 1.71 endophthalmitis cases per 1,000 surgeries; the remaining states had lower rates, which resulted in wider confidence intervals.

According to the study, surgeons with low annual cataract surgery volumes and those with fewer years of surgical experience had an increased risk of postoperative endophthalmitis among their patients. In addition, higher risk of endophthalmitis was associated with patients who were 85 and older and those who were male. The authors speculate that the increased risk of endophthalmitis in African Americans and Native Americans could be related to socioeconomic disadvantage and poorer general health in these groups.

The authors conclude that although post–cataract surgery endophthalmitis in the United States is rare—given the large number of surgeries performed every year—the disease should continue to be monitored.


Imaging of Choroidal Nevus With the Enhanced Depth Feature of SD-OCT
Ophthalmology
Published online Jan. 31, 2012

Shah et al. demonstrated that the enhanced depth imaging (EDI) feature of spectral-domain optical coherence tomography (SD-OCT) is a viable technique for obtaining high-resolution images of posteriorly located choroidal nevus. The authors found that the nevus thickness when measured by EDI SD-OCT tended to be thinner than when measured by ultrasonography; they also discovered that 94 percent of choroidal nevi had overlying choriocapillaris thinning. The authors stated that the EDI SD-OCT could provide more precise measurement of nevus thickness as well as more detailed insight regarding the surrounding tissue.

The authors noted, however, that several factors may adversely affect image quality. Of the 104 eyes with choroidal nevus included in this retrospective case series, only 51 (49 percent) showed image detail that could be studied. The remaining 53 cases had suboptimal image acquisition due to patient-related factors, such as advancing age (older than 60 years) and female sex, or nevus-related factors, such as extramacular location and greater maximal basal diameter of the nevus. The authors also pointed to poor patient cooperation or ocular stability as factors that would lead to a reduced image quality.


Creating Choroidal Thickness and Volume Maps Using SD-OCT
Ophthalmology
Published online Jan. 25, 2012

Many studies have used SD-OCT to measure choroidal thickness manually in a point-to-point manner on the subfoveal region. Shin et al. reported a novel method for creating an Early Treatment Diabetic Retinopathy Study (ETDRS)–style topographic map of choroidal thickness and volume by modifying the six radial scan protocol used with SD-OCT. This approach automatically produced high-resolution B-scan images clear enough to visualize the choroidal boundary. The modification specifically involved a semiautomated adjustment of the retinal boundary to the choroidal boundary in each of the six radial B-scans. A topographic map of choroidal thickness and volume was then automatically adjusted by built-in software according to the ETDRS layout. The authors also conducted statistical analysis to compare the choroidal thickness and volume measurements for each ETDRS subfield.

This prospective, noncomparative case series involved 80 eyes from 40 healthy participants. The mean time required for the adjustment was 167.4 ± 15.8 seconds. The mean choroidal thickness of all ETDRS subfields was 285.9 ± 53 µm and the mean total choroidal volume of the entire ETDRS area was 7.72 ± 1.2 mm3. The nasal outer macula area was significantly smaller than any other ETDRS subfield except for the adjacent superior and inferior outer macula subfields.

The authors conclude that this simple approach to creating topographical thickness and volume maps allows for more comprehensive choroidal evaluation in research and clinical practice.


American Journal of Ophthalmology

Alpha Antagonists and Intraoperative Floppy Iris Syndrome
April’s AJO

In a prospective, case-control study, Theodossiadis et al. described a reliable method to acquire quantitative pupil measurements. In addition, they analyzed the similarities and differences in pre- and post-dilation pupil dynamics in patients on either alfuzosin or tamsulosin and found that tamsulosin is more potent than alfuzosin in inducing intraoperative floppy iris syndrome.

The authors administered tamsulosin and alfuzosin to 15 and 25 patients, respectively, and included 25 control patients in their investigation. Using an electronic pupillometer, the authors recorded resting pupil diameter and subsequent contraction, latency, constriction velocity and dilation velocity. All pupil measurements were performed before and after pharmacologic dilation.

In pre-dilation measurements, they detected a significant decrease in maximum pupillary diameter in the tamsulosin group, as well as a decrease in the mean percentage of diameter reduction after stimulation. Alfuzosin also induced a significant decrease in maximum pupillary diameter. Constriction velocity was significantly reduced by 0.7 mm/s in the tamsulosin group and by 0.54 mm/s in the alfuzosin group. In terms of post-dilation measurements, maximum and minimum pupil diameters were reduced significantly only in the tamsulosin group.


Effect of General Anesthesia and Strabismus Surgery on Children
April’s AJO

Yang et al. found that general anesthesia with sevoflurane during strabismus surgery generally did not affect the intellectual abilities of complex cortical function in children 5 to 10 years of age. However, some cortical functions related to eye-hand coordination may be affected by transient changes in postoperative stereoacuity.

In this prospective, observational study of 21 children, the authors examined intellectual abilities before and four weeks after surgery using the Kaufman Assessment Battery for Children. The mean length of time that the children had been under general anesthesia was 51.3 minutes. The physicians included four subtests representing intellectual abilities related to complex cortical function: identification of objects in a partially completed picture; reproduction of a presented design by using rubber triangles; selection of a picture that completes or is similar to another picture; and memory for location of pictures presented on a page.

The mean preoperative total score of the four subtests was 49.4. The mean postoperative total score adjusted for potential learning effects and test/retest reliability was 48.1. The change in total postoperative score was not significant. However, the triangle test score decreased significantly after operation, particularly in patients with decreased stereoacuity after surgery.


Positron Emission Tomography/Computed Tomography Evaluation of Patients With Uveal Metastasis
April’s AJO

Commonly used for tumor staging, positron emission tomography/computed tomography (PET/CT) can also aid in detection of the primary cancer in patients with metastatic uveal tumors. In this retrospective, observational case series, Patel and Finger investigated 18 patients with uveal metastatic tumors. Patients had either past medical history of malignancy without known active metastasis or systemic cancer, or no history of malignancy. The whole-body PET/CT was used for cancer staging and as a screening tool to evaluate the intraocular tumor and to evaluate for multiorgan metastatic disease.

PET/CT imaging uncovered previously occult primary nonocular cancers (67 percent of patients), revealed progression of known primary systemic cancer (39 percent) and found multiorgan metastases in all cases. PET/CT findings were used to direct nonocular, confirmatory biopsy in 67 percent of cases. No uveal biopsies were required. PET/CT revealed lymph nodes and bone as the most common metastatic sites. The intraocular tumor was detectable in 28 percent of cases.


Archives of Ophthalmology

Prevention and Management of Graft Detachment in Descemet Membrane Endothelial Keratoplasty
March’s Archives

Dirisamer et al. described the prevention and management of graft detachment after Descemet membrane endothelial keratoplasty (DMEK); the measures they found to be preventive include checking that the donor graft is properly centered and unfolded at the time of surgery with adequate air bubble support. They also found that larger detachments may require subsequent intervention, either with early rebubbling or later retransplantation.

In this study, 150 consecutive eyes with Fuchs endothelial dystrophy underwent DMEK; the authors studied the incidence and type of graft detachment at one, three, six, nine, 12 and 24 months after surgery.

Thirty-six eyes experienced some type of graft detachment; only half of these caused visual impairment or required reoperation. Small detachments of less than one-third of the graft area were most common—usually caused by inward folds in the donor membrane at the time of surgery—and did not interfere with either corneal clearance or final visual acuity. Larger detachments of greater than one-third of the graft area were less frequent but more likely to be visually significant.


Glaucoma-Related Adverse Events in the Infant Aphakia Treatment Study
March’s Archives

Beck et al. examined the glaucoma- related adverse events noted in the first year of the Infant Aphakia Treatment Study (IATS). They found that younger patients with persistent fetal vasculature seem more likely to develop a glaucoma-related adverse event in the first year following surgery for congenital cataract. Modern surgical techniques, either with or without an IOL, do not eliminate the early development of glaucoma.

The IATS evaluated the surgical outcomes of 114 infants with unilateral congenital cataract between 1 and 6 months of age. The authors randomized the infants to surgery with or without an IOL and analyzed one-year results of glaucoma-related adverse events. A total of 14 patients experienced a glaucoma-related adverse event: 10 developed glaucoma, and four were noted to be glaucoma suspects. Nine patients in the IOL group developed a glaucoma-related adverse event compared with five in the aphakic group. A multivariate analysis of risk factors for the development of a glaucoma-related adverse event revealed a higher risk in children with persistent fetal vasculature and for each month of age younger at cataract surgery.

The authors conclude that a five-year follow-up for the IATS will likely demonstrate more glaucoma-related adverse events, based on previous studies in this patient population.


Retinal Microvascular Signs and Disability
March’s Archives

Accumulating evidence suggests that small-vessel disease may play an important role in age-related functional loss. Kim et al. examined the records of 1,487 nondisabled older adults in the Cardiovascular Health Study to determine whether small-vessel disease assessed in retinal vessels would predict future disability. They found that the presence of two or more retinal microvascular signs may be an early marker of microvascular disease that portends a future risk of disability in older adults.

The authors evaluated retinal photography for the presence of generalized arteriolar narrowing, generalized venous widening, retinopathy, arteriovenous nicking and focal arteriolar narrowing. They assessed individual and total number of retinal microvascular signs, looking for associations with disability in basic activities of daily living.

The prevalence of retinal microvascular signs ranged from 7 to 10 percent, and approximately 7 percent of patients had two or more retinal signs. During the follow-up of up to 7.8 years, participants with two or more signs had a 1.5-fold higher rate of disability than did those with no signs or one sign, independent of carotid atherosclerosis and other risk factors. Ophthalmology summaries are written by Lori Baker Schena, EdD, 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.
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Ophthalmology summaries are written by Lori Baker Schena, EdD, 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

Role of Epigenetic Mechanisms in Retinoblastoma
Nature
2012;481(7381):329-334

Zhang et al. have found that epigenetic mechanisms may play a role in the development of retinoblastoma tumors. Specifically, they identified the proto-oncogene spleen tyrosine kinase (SYK) as an important oncogene in this disease. SYK is upregulated in retinoblastoma and is necessary for the survival of the tumor cells. The gene may also serve as a novel therapeutic target—the researchers utilized small-molecule inhibitors to induce retinoblastoma tumor cell death in vitro and in vivo.

Previous studies have shown that retinoblastoma is initiated by the biallelic loss of the RB1 gene, with the tumors progressing very quickly and aggressively following the gene’s inactivation. However, the authors of this study, using whole-genome sequencing techniques, demonstrated that the retinoblastoma genome is stable. This finding is surprising because prior research had demonstrated that functional inactivation of RB1 can cause genomic instability. Consequently, genomic instability is not a hallmark of retinoblastoma, nor does it explain rapid tumor progression. Instead, the authors propose that epigenetic mechanisms contribute to the development of retinoblastoma tumors.


Cosmetic Iris Implants Associated With Severe Ocular Complications
Journal of Cataract and Refractive Surgery
Published online Jan. 13, 2012

Hoguet et al. present a case series of 14 eyes of seven patients who had the NewColorIris (Kahn Medical) implanted in Panama. (The device is not FDA approved.) The authors reported that the complications arising from these implants can be serious and result in severe ocular morbidity. Patients presented with decreased visual acuity, increased IOP, iritis and corneal edema. Although symptoms generally stabilized following removal of the implants, more than half of the eyes required additional medical and surgical treatment to control IOP and corneal decompensation.

The NewColorIris implants are a one-piece annular silicone iris diaphragm placed in the anterior chamber directly in front of the iris. In addition to manufacturing issues with the implants, problems occurred when implants decentered relative to the pupil in many of the eyes in this series. The authors also commented on subsequent ocular problems despite implant explantation. At the time this study was written, nine of the 14 eyes required subsequent surgery.


Vorinostat to Prevent and Treat Laser-Induced Corneal Haze
Journal of Refractive Surgery
Published online Feb. 15, 2012

In this study, Tandon et al. investigated the efficacy and safety of topical vorinostat, a deacetylase inhibitor, in the treatment of laser-induced corneal haze. They found that its application significantly reduced haze formation without evidence of toxicity.  

The authors produced corneal haze in vivo in rabbits with 9-D photorefractive keratectomy (PRK), and in vitro by activating fibrosis in cultured human and rabbit corneal fibroblasts with transforming growth factor beta 1 (TGF1). They applied vorinostat once for five minutes on rabbit cornea immediately after PRK, and applied vorinostat for five minutes or 48 hours to human/rabbit corneal fibroblasts. The authors used slit-lamp microscopy and trypan blue to determine vorinostat toxicity and real-time polymerase chain reaction and immunocytochemistry to measure its efficacy.

Four weeks after the single five-minute vorinostat topical application on the rabbit cornea following PRK, the researchers found significantly reduced corneal haze and fibrotic marker proteins without evidence of redness, swelling or inflammation. Vorinostat reduced TGF1-induced fibrosis in human and rabbit corneas without altering cellular viability, phenotype or proliferation.


Embryonic Stem Cells Used to Treat Macular Degeneration
The Lancet
Published online Jan. 24, 2012

Schwartz et al. report findings from a safety and tolerability study demonstrating that human embryonic stem cell (hESC)–derived cells might be safely transplanted into human patients. The study involved transplanting a low dose of retinal pigment epithelium (RPE) cells generated from hESCs into one eye of one patient with Stargardt’s macular dystrophy and one eye of one patient with dry age-related macular degeneration.

The authors selected a submacular injection site where the macular anatomy was still present, thus maximizing the chance that the transplanted cells would integrate with the native RPE and rescue compromised perimacular tissue. Structural evidence showed that cells had attached and continued to persist during the four-month study period. In addition, there were no signs of hyperproliferation, abnormal growth or immune-mediated transplant rejection in either patient.

The patient with Stargardt’s macular dystrophy improved from 0 to 5 letters on the Early Treatment Diabetic Retinopathy Study (ETDRS) visual acuity chart, and the patient with AMD improved from 21 ETDRS letters to 28. Neither patient lost vision during the observation period.
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Roundup of Other Journals is written by Lori Baker Schena, EdD, and edited by Deepak P. Edward, MD.



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