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July/August 2008

 
Journal Highlights
New Findings from Ophthalmology, AJO and Archives
 
 

July’s Ophthalmology:

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Roundup of Other Journals:

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Ophthalmology

Adverse Outcomes Following Glaucoma Surgery
July’s Ophthalmology

Stein et al. conducted a longitudinal cohort analysis to determine whether postoperative adverse outcome rates for the major incisional glaucoma surgeries (primary trabeculectomy, trabeculectomy with scarring and glaucoma drainage device implantation) reflected findings previously reported in smaller observational series and clinical trials.

The investigators used Medicare data from a 15-year period involving beneficiaries aged 68 and older who underwent these procedures between 1994 and 2005. Serious adverse outcomes were defined as retinal detachment, endophthalmitis and choroidal hemorrhage, and less serious adverse outcomes were choroidal detachment, corneal edema and hypotony. Findings showed that the risk for adverse outcomes was higher in glaucoma drainage device implantation than in primary trabeculectomy or trabeculectomy with scarring, reflecting the previously reported findings from similar studies in the literature.

The investigators caution that the study does not address how many patients had useful eyesight that was saved by the surgery. Consequently, treatment decisions should be based on both the benefits and possible adverse outcomes of each type of surgery.


IOP Fluctuation and Visual Field Progression
July’s Ophthalmology

Using data from the Advanced Glaucoma Intervention Study, Caprioli and Coleman found that long-term fluctuation in IOP is associated with visual field progression in individuals with low mean IOP, but not in those with high mean IOP. The investigators only included eyes that had one surgical intervention. To calculate the mean IOP and IOP fluctuation in this study, the investigators used only IOPs from the surgical intervention up until the time of first evidence of a declining visual field.

The study involved 301 eyes of 301 patients. Visual field progression was detected in 78 eyes (26 percent) and associated with three variables: greater IOP fluctuation, argon laser trabeculoplasty and older age. In their model, IOP fluctuation in the low mean IOP group was associated with visual field progression. This association was not seen in the high mean IOP group.

Given these findings, the authors suggest that clinicians may want to rethink target pressure, perhaps considering IOP modulation rather than IOP reduction when exploring treatment options.


Glaucomatous Visual Field Loss May Not Lead to Total Blindness
July’s Ophthalmology

A retrospective chart review study by Much et al. demonstrated that the prognosis for treated patients with end-stage glaucoma may be better than previously thought. This research focused on a predominantly African-American population with end-stage glaucomatous visual field loss defined by a central island of vision of 10 degrees in radius or less.

Investigators included 84 eyes of 64 patients (78 percent African-American) with an average follow-up of 8.34 ± 3.1 years. They found that 14 eyes lost more than three lines of visual acuity with eight of these eyes progressing to a visual acuity of 20/200 or worse. Few eyes in the study experienced a complete blackout of their central visual field due to glaucoma.

The authors conclude that progression to blindness is not the norm in treated patients with end-stage glaucomatous visual field loss, and they encourage ophthalmologists to share these relatively optimistic findings with patients.


Use of Electronic Health Records Not Widespread
July’s Ophthalmology

A study by Chiang et al. involving Academy members indicates that a relatively small fraction of ophthalmologists is using an electronic health record (EHR) system. However, these early technology adopters report high levels of satisfaction, as their systems tend to improve practice efficiency and reduce costs.

The researchers randomly selected 3,796 Academy members based on geography and obtained 592 replies. Overall, 12 percent of the practices surveyed had already implemented an EHR, 7 percent were in the process of adopting one and 10 percent planned to do so within the next year. Of those who used an EHR in their practice, 69 percent were satisfied or extremely satisfied with their system, 64 percent reported increased or stable overall productivity, 51 percent reported decreased or stable overall costs and 76 percent would recommend a similar system to fellow ophthalmologists.

The investigators conclude that while acceptance by ophthalmologists is currently low, widespread adoption of EHR may be necessary to optimize the key benefits of the system.


Amblyopia and Strabismus in African-American and Hispanic Children
July’s Ophthalmology

The Multi-Ethnic Pediatric Eye Disease Study (MEPEDS) was designed to evaluate the prevalence of strabismus, amblyopia and refractive error in 12,000 children between the ages of 6 and 72 months from four ethnic groups: African-American, Asian-American, Hispanic/Latino and non-Hispanic white in Los Angeles County, Calif.

This subreport focuses on the African-American and Hispanic/Latino populations, including 3,007 children from each ethnic group. The researchers identified strabismus in 2.4 percent of Hispanic/Latino children and 2.5 percent of African-American children. The condition was more prevalent in older children. Amblyopia was found in 2.6 percent of Hispanic/Latino children and 1.5 percent of African-American children—a statistically significant difference. Seventy-eight percent of the amblyopia cases were attributed to refractive error, and the prevalence of amblyopia did not vary with age.

These findings may help optimize timing and modality of preschool vision screening programs given that refractive error caused most of the amblyopia cases in this population and that the prevalence of amblyopia is stable by four years of age.


American Journal of Ophthalmology

Incisions for Anterior Capsule Contraction
July’s AJO

Hayashi et al. investigated the effect of two or three Nd:YAG laser relaxing incisions made in the anterior capsular rim to prevent anterior capsule contraction.

One hundred patients scheduled for bilateral cataract surgery were randomized to one of two groups: 1) two or three relaxing incisions in the left eye and no incisions in the right eye, and 2) relaxing incisions in the right eye and no incisions in the left eye. The relaxing incisions were all performed three days after the cataract surgery. The anterior capsule opening area was measured using Scheimpflug photography immediately after capsulotomy and at one, three and six months after capsulotomy. Along with calculating the reduction of the opening area, the authors determined the degree of IOL decentration and tilt, and the amount of posterior capsule opacification.

The investigators found no significant difference in the anterior capsule opening area between fellow eyes at baseline (three days after cataract surgery). In patients who underwent two incisions, no significant difference was found between fellow eyes in the opening area or the percentage of reduction throughout follow-up. In patients who underwent three incisions, the opening area in eyes with capsulotomy was significantly greater than that in fellow eyes without capsulotomy, and the percentage reduction was significantly smaller in eyes with capsulotomy than in eyes without capsulotomy. No significant differences were found in the IOL decentration and tilt, or in posterior capsule opacification.


Sneezing Reflex With Sedation and Anesthetic Injection
July’s AJO

Ahn et al. compared the frequency of reflex sneezing occurring during periocular anesthetic injections with and without intravenous sedation.

In a retrospective study of 722 patients undergoing oculoplastic surgical procedures, the patients who received a periocular anesthetic injection under intravenous sedation served as the test group of 381 subjects. Those who received a periocular anesthetic injection without intravenous sedation served as the control group of 341 subjects. The absence or presence of reflex sneezing in both groups was recorded and compared using chi-square analysis.

Of the 381 patients who received periocular anesthetic injections under intravenous sedation, 19 exhibited a vigorous sneeze. Conversely, none of the 341 patients who received periocular anesthetic injections without intravenous sedation sneezed.

The authors point out that all operating room personnel should be aware of this unusual and potentially dangerous sneeze phenomenon in order to reduce potential ocular complications.


Risk Factors for Complications After Congenital Cataract Surgery
July’s AJO

Kuhli-Hattenbach et al. investigated individual risk factors for the development of complications in children undergoing pediatric cataract surgery.

The authors reviewed the records of 67 eyes of 44 children who underwent congenital cataract surgery in the first 18 months of life. They performed a limbal-approach bimanual lens aspiration, a posterior capsulorhexis and an anterior vitrectomy without IOL implantation for all children. The mean follow-up period was 39 months.

The most frequent postoperative complications were late-onset open-angle glaucoma (11 percent) and vitreous hemorrhage (11 percent), whereas early-onset glaucoma (5 percent) was less common. Secondary cataract was observed in seven eyes (9 percent). A family history of aphakic glaucoma in first-degree relatives, cataract surgery in the first three months of life and nuclear cataracts were strong predictors of late-onset glaucoma. Secondary cataract formation was associated strongly with lensectomy in the first five months of life. The diagnosis of postoperative hemorrhages was associated significantly with the presence of persistent fetal vasculature.

The authors conclude that potential risk factors for complications after congenital cataract surgery include young age at the time of surgery, a family history of aphakic glaucoma, nuclear cataract or persistent fetal vasculature syndrome. They also note that it is not clear how the results might differ if an IOL had been implanted at the time of surgery.


Intrastromal Voriconazole and Fungal Keratitis
July’s AJO

Prakash et al. evaluated the role of intrastromal injection of voriconazole in the management of deep recalcitrant fungal keratitis.

Their study included three eyes of three patients with deep stromal recalcitrant fungal keratitis not responding to topical antifungal medications. Patients received voriconazole 50 µg/0.1 ml injected circumferentially around the fungal abscess in the corneal stroma. Before the intracorneal injection, all three eyes had gradually worsening lesions on topical medications.

After the voriconazole injection, a faster reduction in the size of corneal infiltration was documented and a complete resolution of the ulcers was seen within three weeks in all cases. The authors conclude that targeted delivery of voriconazole by intracorneal injection may be an effective method to treat cases of deep-seated recalcitrant fungal keratitis responding poorly to conventional treatment modalities.


Archives of Ophthalmology

Retinal Vein Occlusion and Atherosclerosis Risk Factors
May’s Archives

O’Mahoney et al. completed a meta-analysis of 21 observational studies comprising 2,915 persons with retinal vein occlusion (RVO) and 28,646 unaffected controls in an effort to determine the association between RVO and three conditions: hypertension, diabetes mellitus and hyperlipidemia.

They found that both hypertension and hyperlipidemia were consistently associated with RVO in a pronounced manner, while diabetes mellitus had a less pronounced association. The calculated population-attributable risk percent for RVO was 48 percent for hypertension, 20 percent for hyperlipidemia and 5 percent for diabetes mellitus.

They note that it remains to be determined whether lowering blood pressure and/or serum lipid levels can improve visual acuity or the complications of RVO.


Distribution of Artificial Tears on Ocular Surface
May’s Archives

Wang et al. studied the effects of artificial tear viscosity on tear film thickness, upper and lower tear menisci, and tear volume using real-time optical coherence tomography.

The investigators imaged the central tear film and tear menisci before and immediately after the instillation of different artificial tears in 40 eyes of 20 healthy subjects.

Carboxymethylcellulose sodium, 1 percent (viscosity, 70 centipoises), propylene glycol, 0.3 percent (10 cP), polyethylene glycol, 0.4 percent (10 cP), carboxymethylcellulose, 0.5 percent (3 cP), and isotonic sodium chloride solution (1 cP) were tested on two consecutive days. All measurements, including tear film thickness, the height, radius and area of the tear meniscus, and the estimated tear volume, were obtained immediately upon instillation and five, 20, 40 and 60 minutes after instillation.

At instillation, all artificial tears and saline caused an increase in all tear variables. Tear film thickness remained significantly elevated for all drops at five minutes and returned to baseline at 20 minutes. Other variables returned to baseline at five minutes. Comparing the different drops, tear film thickness and lower meniscus variables at instillation were increased with the more viscous drops.


Genetic Mutations and Endothelial Dystrophy
May’s Archives

Hemadevi et al. studied the association of solute carrier family 4 (sodium borate cotransporter) member 11 (SLC4A11) gene mutations with autosomal recessive congenital hereditary endothelial dystrophy (CHED2).

Twenty-six affected individuals in 20 families with CHED2 (along with their available unaffected family members) were selected for the study. The investigators performed DNA extraction from blood, polymerase chain reaction amplification and direct sequencing of all the exons of the SLC4A11 gene.

Of 10 mutations observed, six were novel, one of which involved a complete deletion of exon 6 (identified for the first time in SLC4A11). The mutations cosegregated with the disease phenotype and were absent in 200 ethnically matched control chromosomes analyzed.

The authors confirmed the role of SLC4A11 gene in causing CHED2. Clinical examination did not reveal any considerable variability in disease expressivity in patients carrying SLC4A11 mutations. In the nine families in which no mutation was identified in the coding region, no significant changes in the promoter region of SLC4A11 were detected. They conclude that extensive linkage analysis may reveal the modifier genes involved in causing CHED2 in the SLC4A11 mutations unidentified in nine families.


Health Literacy in Patients With Glaucoma
May’s Archives

Juzych et al. assessed the relationship between health literacy and compliance, disease awareness and disease progression in patients with glaucoma.

The investigators conducted a study of 204 English-speaking patients treated for glaucoma for at least one year. Health literacy was assessed using the standardized Test of Functional Health Literacy in Adults. A questionnaire assessed patients’ demographic information and glaucoma understanding. A medical record review was conducted to record parameters indicating glaucoma severity.

Of the 204 participants, 102 (50 percent) were categorized as having poor functional health literacy and an equal number had adequate health literacy. The poor health literacy group showed significant differences in income, education, medication compliance, glaucoma understanding and missed appointments compared with the adequate health literacy group. Patients with poor health literacy showed a greater visual field loss on initial presentation compared with the adequate health literacy group and significantly worse visual field parameters when comparing pattern standard deviations on the recent and the initial visual fields.

The authors conclude that patients with poor health literacy have poorer compliance, worse disease understanding and greater disease progression compared with the adequate health literacy group.
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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

OCT and Fundus Photographic Assessments in Diabetic Macular Edema
Investigative Ophthalmology & Visual Science
2008;49:1745–1752

In patients with diabetic macular edema, optical coherence tomography provides quantitative estimates of retinal thickness at multiple points within the macular region. From these data, a retinal thickness map can be created. Along with a photographic DME severity scale, stereoscopic fundus photographs can identify the location and assess the severity of retinal thickening and hard exudates. Davis et al. conducted a study to determine whether a correlation exists between OCT and fundus photography when assessing retinal thickening in DME.

The researchers obtained OCT, fundus photos and BCVA measurements in both eyes of 263 individuals participating in a clinical trial evaluating two photocoagulation techniques. They found only moderate correlations between OCT and the fundus photography. While OCT provided a more sensitive and reproducible measure of retinal thickening, it was not as effective in documenting morphologic features compared with fundus photos. However, changes in each of these measures may not reflect changes in BCVA, so this comparison may not be relevant.


Measuring Macular Thickness With OCT
Investigative Ophthalmology & Visual Science
Published online April 30, 2008

Leung et al. compared macular thickness measurements taken with both time-domain and spectral-domain optical coherence tomography. Time-domain OCT collects 400 axial measurements per second with an axial resolution of about 10 µm. In contrast, the spectral-domain OCT scan rate is at least 20,000 axial measurements per second with an axial resolution of 5 µm. Both systems use an interferometer to measure the echo time delay of backscattered light signals.

The researchers studied 35 healthy individuals. In one randomly selected eye in each subject, three serial macular measurements were taken from both time-domain OCT and spectral-domain OCT. While both the time-domain and spectral-domain OCTs produced low variability for macular thickness measurements, the spectral-domain OCT demonstrated better measurement repeatability for total and regional macular thicknesses. This might indicate that the spectral-domain OCT could possibly help detect changes during serial monitoring of macular diseases and glaucoma.


QuantiFERON-TB Gold Testing Reviewed in Ophthalmic Patients
Eye
Published online May 2, 2008

The second-generation QuantiFERON-TB Gold (QFT-G) test is designed to detect tuberculosis infection with increased specificity. Itty et al. reviewed the charts of ophthalmic patients at the Mayo Clinic who underwent QFT-G tests in a three-year period.

Of the 27 QFT-G tests ordered, 13 (48 percent) were negative, six (22 percent) were indeterminate, two (7 percent) were reordered, four (15 percent) were positive and reflected infection, and two (7 percent) were initially positive but negative when retested. Of the four positive patients, three received treatment. From an ophthalmic standpoint, one patient had tuberculosis iritis, one had retinal vasculitis and hemorrhage, one had asymptomatic tuberculosis but was on immunosuppressive therapy and the fourth had received previous treatment for a latent infection.

The authors point out that while the QFT-G test was able to detect tuberculosis infection in 15 percent of patients, the test could not determine whether the tuberculosis was active or latent. They recommend that QFT-G would make an acceptable substitute for purified protein-derivative testing in patients with uveitis who had prior Bacille Calmette Guérin (BCG) vaccination and in immunocompromised patients. In addition, if a patient tests positive with the QFT-G test but is at low risk for tuberculosis, he or she should be retested.


Genetic Association Between Diabetic Eye and Kidney Complications
Proceedings of the National Academy of Sciences
2008;105:6998–7003

Tong et al. point out that proliferative diabetic retinopathy (PDR) and end-stage renal disease (ESRD) constitute two of the most common and severe complications in patients with diabetes. Because both a high concordance and a strong familial aggregation exists with these two complications, a common underlying genetic mechanism may be involved.

Erythropoietin (EPO) is a potent angiogenic factor linked to the diabetic human and mouse eye. Through a combination of case-control association and functional studies, the authors identified an association between a functional EPO promoter polymorphism (rs1617640) and PDR and ESRD. They caution that the study was limited to European-Americans and thus this finding may not pertain to other ethnic groups. Therefore, further replication studies may be needed.
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Roundup of Other Journals is written by Lori Baker Schena and edited by Deepak P. Edward, MD.