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Journal Highlights
New Findings from Ophthalmology, AJO and Archives
 
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Ophthalmology

Comparison of Limbus- and Fornix-Based Trabeculectomy Outcomes and Side Effects
Ophthalmology
Published online Jan. 9, 2012

In a retrospective case series comparing limbus- and fornix-based trabeculectomy, Solus et al. found that the two treatment approaches had comparable success rates in terms of controlling IOP but differed in bleb morphology and rates of late, undesirable effects.

This investigation included patients who underwent trabeculectomy between May 2000 and October 2008. Surgeons performed the limbus-based operations during the first four years and the fornix-based operations during the last four years. For each follow-up visit, the investigators defined success as the need for no further glaucoma procedures. Data were collected by chart review and by clinical examination during the last patient visit.

Blebs after limbus-based surgery were more likely to be graded as higher and were avascular and more susceptible to late infection. In contrast, fornix-based flaps demonstrated more symptomatic hypotony but no greater proportion of surgical revisions to address low IOP. Four percent of eyes had late-onset bleb leaks within four years after both surgical approaches. However, limbus-based blebs developed leaks significantly later than did the fornix-based flaps. Cataract surgery was common in both types of trabeculectomy, but it was done more often and earlier in patients who had undergone the fornix-based procedure.


SD-OCT Sheds Light on Optic Disc Margin Anatomy in Glaucoma Patients
Ophthalmology
Published online Jan. 4, 2012

In this study, Reis et al. used spectral- domain optical coherence tomography (SD-OCT) to characterize optic nerve head (ONH) anatomy as it relates to the clinical optic disc margin. They found that what is clinically identified as the disc margin is rarely a single structure and is most likely not the innermost edge of Bruch’s membrane. Instead, it is some aspect of Bruch’s membrane and border tissue or, less commonly, the Bruch’s membrane opening or border tissue alone.

The authors included 30 open-angle glaucoma patients (10 with focal disc damage, 10 with diffuse disc damage and 10 with sclerotic disc damage) and 10 controls. They analyzed high-resolution radial SD-OCT B-scans centered on the ONH at each clock hour. For each scan, the investigators classified the border tissue of Elschnig for obliqueness (internally oblique, externally oblique or nonoblique), and they looked for the presence of Bruch’s membrane overhanging the border tissue. Optic disc stereophotographs were co-localized to SD-OCT data with customized software. The investigators also computed the frequency with which the disc margin identified in stereophotographs coincided with the Bruch’s membrane opening, Bruch’s membrane/border tissue or border tissue in the B-scans at each clock hour.

Although 28 of the glaucoma patients had two or more border tissue configurations, the most predominant type was internally oblique—primarily superiorly and nasally—frequently with Bruch’s membrane overhang. Externally oblique border tissue was less frequent, and was observed mostly inferiorly and temporally. In control subjects an internally oblique configuration around the disc predominated. Although the configurations were not statistically different between the glaucoma patients and controls, they were statistically different among the three glaucoma groups. At most locations, the structure most frequently identified by SD-OCT as the disc margin was some aspect of Bruch’s membrane and border tissue external to the Bruch’s membrane opening. Bruch’s membrane overhang was regionally present in the majority of patients with glaucoma and in controls; however, in most cases it was not visible as the disc margin.


Vitrectomy Without Gas Tamponade or Laser Treatment in Macular Detachment With Optic Disc Pit
Ophthalmology
Published online Jan. 4, 2012

In a case series of eight patients (eight eyes), aged 8 to 56 years, with unilateral macular detachment associated with optic disc pit, Hirakata et al. found that inducing a posterior vitreous detachment (PVD) without a gas tamponade or laser photocoagulation appears to be effective treatment.

In all eyes, the investigators performed pars plana vitrectomy with induction of a PVD, but they did not use photocoagulation or gas injection in any eye during the surgery. Patients were followed for 10 to 46 months after surgery.

Although complete retinal reattachment was achieved in seven eyes, full resolution of the detachment took up to about one year. The one eye in which macular detachment failed to resolve completely underwent revision of vitrectomy with a gas tamponade and laser photocoagulation in the peripapillary area. In the early postoperative period, despite persistent macular detachment, visual acuity improved in seven eyes. These improved acuities corresponded with remodeling of the photoreceptor outer segments on OCT and the appearance of granular hyperfluorescence on fundus autofluorescence imaging.


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the following websites:

Ophthalmology
www.aaojournal.org

American Journal of Ophthalmology
www.ajo.com

Archives of Ophthalmology
archopht.ama-assn.org


American Journal of Ophthalmology

Full-Cycle Steam Sterilization in Ophthalmic Surgery
March’s AJO

Carpel et al. found that, in a high-volume eye facility, the incidence of presumed postoperative infection associated with unwrapped and wrapped full-cycle steam sterilization was identical.

In this comparative study, the authors reviewed two consecutive groups—approximately 19,000 ophthalmic surgical patients each—for postoperative infection. The surgical instruments for both groups were sterilized using full-cycle steam sterilization. Instruments for the first group were unwrapped and sterilized adjacent to the operating room. Instruments for the second group were wrapped and sterilization was conducted at a central facility.

In the unwrapped sterilization group, 17 presumed postoperative infections were identified, compared with nine presumed infections in the wrapped sterilization group. The difference was not found to be statistically significant. Similarly, differences found in the incidence of culture-positive cases of endophthalmitis (five for unwrapped vs. three for wrapped) were not statistically significant.

According to the authors, this study provides evidence that if eye surgical facilities carefully clean surgical instruments and follow the industry and manufacturer guidelines, they can successfully use either of these two methods of sterilization.


IOP Measurement Following Penetrating Keratoplasty
March’s AJO

In situations where Goldmann applanation tonometry readings are difficult to obtain, Chou et al. found that the TonoPen XL and the Pascal dynamic contour tonometer are the most suitable alternatives for measuring intraocular pressure (IOP) following penetrating keratoplasty (PK).

The authors selected 31 eyes of 31 participants with previous PK and designed a prospective, cross-sectional study to compare IOP measurements using Goldmann applanation tonometry, the TonoPen, the Pascal tonometer and an ocular response analyzer. They also used Scheimpflug tomography to analyze the effects and correlation of central corneal thickness (CCT) and curvature on these measurements.

Mean age was 44.5 years, mean time since PK was 27.7 months, mean CCT was 585 ?m, and mean corneal astigmatism was 5.5 D. There was no significant difference in IOP as measured by Goldmann applanation tonometry and the TonoPen; however, both the Pascal tonometer and ocular response analyzer measured significantly higher IOPs than did the Goldmann applanation tonometer. The ocular response analyzer showed the least agreement with Goldmann applanation tonometry. No instruments correlated significantly with CCT. Only the Pascal tonometer showed no significant correlation with corneal astigmatism.


Delayed- vs. Acute-Onset Endophthalmitis After Cataract Surgery
March’s AJO

Shirodkar et al. found that patients with delayed-onset endophthalmitis generally presented with better initial visual acuities and had a lower frequency of hypopyon than did acute-onset patients.

In a large, retrospective, consecutive case series of patients who developed endophthalmitis after cataract surgery, the investigators classified patients as having either acute-onset endophthalmitis (less than six weeks after surgery) or delayed-onset endophthalmitis (more than six weeks after surgery).

A total of 118 patients met study criteria: 26 delayed-onset cases and 92 acute-onset cases. The presenting visual acuity was less than 5/200 in 31 percent of delayed-onset cases versus 89 percent of acute-onset cases. Hypopyon was found in 46 percent versus 80 percent, respectively. The most commonly cultured organisms were Propionibacterium acnes in the delayed-onset group and coagulase-negative Staphylococcus in the acute-onset group.

Of patients with the most frequent isolate for their category, 91 percent of the delayed-onset group had VA of better than 20/100, compared with 56 percent of the acute-onset group. In delayed-onset cases, the IOL was removed or exchanged in 19 of 26 cases. Of these 19 cases, 13 achieved a visual outcome of better than 20/100.


Oxidative Stress and Genetic Variants in Age-Related Macular Degeneration
March’s AJO

Brantley et al. investigated the interaction of genes and environment in AMD and found a relationship between a plasma biomarker of oxidative stress—cystine—and complement factor H (CFH) genotype.

In this prospective, case-control study, the researchers compared plasma levels of oxidative stress biomarkers in AMD patients with controls and evaluated a potential relationship between biochemical markers of oxidative stress and AMD susceptibility genotypes. The authors determined plasma levels of oxidative stress biomarkers in 77 AMD patients and 75 controls, and then measured cysteine, cystine, glutathione, isoprostane and isofuran. Participants underwent genotyping for polymorphisms in CFH and age-related maculopathy susceptibility 2 genes.

Cystine was elevated in AMD patients compared with controls. After adjustment for age, sex and smoking, this association was not significant. In all participants, cystine levels were associated with the CFH polymorphism rs3753394 as well as an eight-allele CFH haplotype after correction for age, gender and smoking. None of the other plasma markers were related to AMD status.

These data suggest a potential as association between inflammatory regulators and redox status in AMD pathogenesis.


Archives of Ophthalmology

Simplified Lateral Transposition Procedures for Abduction Limitation
February’s Archives

In this case review, Mehendale et al. present a simplified transposition procedure for treatment of patients with severe abduction limitation. The authors demonstrated that a superior rectus transposition may be performed without the need for simultaneous surgery on the inferior rectus muscle. They found that simplifying the procedure allowed for more surgical options, including simultaneous, adjustable recession of the medial rectus muscle to titrate the effect of the procedure.

Lateral transposition procedures for abduction limitation have traditionally been thought to require combined repositioning of the superior rectus and inferior rectus muscles. The authors modified this approach by performing a full, augmented transposition of only the superior rectus muscle; in most cases, this was combined with an adjustable medial rectus recession. They then evaluated outcomes in 17 patients, including 10 with Duane syndrome and seven with sixth nerve palsy.

Overall, the angle of head turn improved from 28 to 4 degrees, and abduction improved from –4.3 to –2.7 units. These results were similar to those reported in studies of transposition of both superior and inferior rectus muscles. None of the patients with Duane syndrome developed new vertical deviations, although such deviations did occur in two patients with sixth nerve palsy (both of whom had additional complicating factors). Vertical gaze was preserved, and torsional diplopia did not develop in any patient.

The authors recommend superior rectus transposition for patients with profound abduction limitation in which there is no reasonable chance that a horizontal rectus muscle procedure alone will be satisfactory. They note that this approach is particularly advantageous in patients with contracture of the medial rectus muscle because it allows for a simultaneous medial rectus recession without greatly increasing the risk of anterior segment ischemia.


Retinal Tears and Detachments in Transconjunctival vs. Standard Vitrectomy
February’s Archives

Covert et al. conducted a retrospective case series of patients undergoing vitrectomy for macular pucker or macular hole over a seven-year period. In this study, 211 patients treated with transconjunctival cannulated vitrectomy (20-gauge, 23-gauge or 25-gauge) were compared with 204 patients treated with standard 20-gauge vitrectomy.

The authors found that patients who had transconjunctival vitrectomy were much less likely to experience intraoperative retinal tears than those who had standard vitrectomy. Patients who underwent transconjunctival vitrectomy were also less likely to develop postoperative retinal detachment; however, this finding did not reach statistical significance. Patients with macular hole were 2.7 times more likely to experience intraoperative retinal tear formation during either vitrectomy than those with macular pucker.

The study design allowed for the calculation of risk ratios for the development of intraoperative retinal tears and postoperative retinal detachments as they related to several factors. These factors included surgical approach, preoperative diagnoses, comorbidities and intraoperative variables such as the use of hyaloid stripping and gas tamponade.
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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

New Digital Goldmann Applanation Tonometer Proves Safe and Reliable
British Journal of Ophthalmology
2012;96(1):42-46

After more than a half century of use, the Goldmann applanation tonometer (GAT) has entered the digital age, prompting Egli et al. to compare the standard device with the new digital counterpart.

They specifically tested the variability of consecutive measurements between the two tonometers, as well as device safety. The authors found that the digital GAT is as reliable and safe as the classic GAT and that the IOP measurement values correlate well between the devices. In addition, the digital GAT offers users a digitized display and wireless data transfer to an electronic patient record. The display of values up to the first decimal digit was not necessarily associated with a more precise measurement, but may offer an additional comfort compared with the scale of the classic GAT.

For this study, the investigators examined 250 eyes of 125 patients, including patients with healthy eyes as well as those with different types of glaucoma, ocular hypertension, diabetic retinopathy, age-related macular degeneration and other pathologies. Study protocol included noncontact pachymetry, slit-lamp examination and three consecutive measurements from each GAT, with a check for side effects 15 minutes afterward.


Switching Anti-VEGF Drugs Effective in CNV Patients Who Develop Tachyphylaxis
British Journal of Ophthalmology
2012;96(1):14-20

Gasperini et al. have shown that patients undergoing anti-VEGF therapy for choroidal neovascularization (CNV) who develop tachyphylaxis to ranibizumab or bevacizumab may respond favorably to treatment with the other anti-VEGF drug. However, it may take multiple injections to achieve this favorable treatment response effect.

In this retrospective review of 26 eyes, the authors defined tachyphylaxis as evidence of initially decreased exudation followed by a lack of further reduction or an increase. Exudation signs included subretinal fluid, pigment epithelial detachment and/or cystoid macular edema.

In these patients, 81 percent (21 eyes) who had been treated with either one of these two anti-VEGF agents experienced an improved response after switching to the other. Some patients required two or three injections before achieving this improved response.

The authors call for a prospective trial in order to better understand tachyphylaxis in anti-VEGF treatment and the optimal approaches to address it.


Quality Nonmydriatic Fundus Photography Obtainable in Children Over Age 3
Journal of the American Association for Pediatric Ophthalmology and Strabismus
2011;15(6):567-572

Given the challenges of conducting ocular funduscopic examination in young children, Toffoli et al. studied the possibilities of obtaining high-quality nonmydriatic fundus photographs in this age cohort. The investigators were able to obtain high-quality photos in more than two-thirds of children over age 3. Adequate-quality fundus photographs were obtained in some children as young as 22 months.

A total of 878 photographs of 212 children ranging in age from 1 to 18 years (median, 6) were included in the study. Using a Likert scale, the authors evaluated ease of fundus photography on a 10-point scale (10 being very easy) and quality on a 5-point scale (5 being ideal quality). The main outcome measure was image quality by age of each child. The median rating for ease of photography was 7 on a 10-point Likert scale. The researchers found a linear relationship between the child’s age and the increasing proportion of ease in photography sessions.

The authors conclude that nonmydriatic ocular fundus photography may be a viable alternative to routine ophthalmoscopy for nonophthalmologists in specific clinical settings, including pediatric clinics.


Visual-Field Change in Ocular Hypertension Treatment Study Patients
Investigative Ophthalmology & Visual Science
Published online Dec. 9, 2011

Using data from the Ocular Hypertension Treatment Study (OHTS), Demirel et al. found that eyes meeting the OHTS definition of the primary open-angle glaucoma (POAG) end point showed significantly faster deterioration of visual field (VF) than eyes not meeting this end point. This occurred whether POAG was initially identified according to VF or optic disc criteria.

Specifically, the researchers demonstrated that hypertensive eyes that develop POAG with both optic disc and VF change experience significantly more rapid VF deterioration than those that develop POAG as defined by either optic disc or VF change. However, the authors also note that the rate of mean-deviation change over time in eyes with ocular hypertension—including those that are converting to POAG—is quite slow.

Given these findings, the authors conclude that the rate of mean-deviation change may not represent the best gauge of change in VF in early-stage POAG.
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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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