EyeNet Magazine



   
 
Journal Highlights
New Findings from Ophthalmology, AJO and Archives
 
 

November's Ophthalmology:

November's American Journal of Ophthalmology:

September's Archives of Ophthalmology:

Roundup of Other Journals:


Ophthalmology

Long-Term Findings in the Early Manifest Glaucoma Trial November’s Ophthalmology
November’s Ophthalmology

The Early Manifest Glaucoma Trial looked at the effect of treatment in reducing progression in patients with open-angle glaucoma. In a follow-up report, Leske et al. show that treatment and follow-up intraocular pressure continue to have a significant influence on progression, regardless of baseline IOP.

Factors such as age, bilaterality, exfoliation and disc hemorrhages had an impact on progression. In addition, the follow-up report revealed new significant vascular predictors on progression, including lower systolic perfusion pressure, lower systolic blood pressure and a history of cardiovascular disease. Thinner central corneal thickness was related to progression.

The authors conclude that these results support the value of CCT as a prognostic factor in patients with higher IOP values, and also confirm the importance of follow-up IOP on progression, regardless of baseline IOP.

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Calculating IOL Power Following Hyperopic Refractive Surgery
November’s Ophthalmology

Chokshi et al. conducted a case series involving 20 eyes from 13 patients to determine the effect of hyperopic excimer refractive surgery on IOL power calculation prior to cataract extraction and IOL placement. The researchers compared seven different methods of IOL power calculation.

They found that calculation with the vertex method was the most accurate with a mean deviation from emmetropia of 0.42 D, followed by the back-calculated method with a deviation of 0.54 D. For previously hyperopic eyes, the authors recommend using the vertex method, the back-calculated method or their own adjustment formula based on average keratometry and spherical equivalent induced by refractive surgery. They mention the advantage of their adjustment formula to average keratometry is that the only preoperative data needed is the spherical equivalent induced by the refractive surgery.

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An Atypical Form of Herpes Keratitis
November’s Ophthalmology

In a six-patient case report, Gabison et al. describe an atypical form of herpes simplex keratitis that they call “archipelago keratitis.” This disease is characterized by marginal corneal ulceration, an underlying stromal inflammatory infiltrate and foci of superficial keratitis disposed in a linear centripetal pattern resembling an archipelago.

The authors noted that all patients in the study had a past history of herpetic epithelial keratitis and/or herpetic vesicles on the ipsilateral lid. Two patients showed evidence of herpes simplex virus (HSV1 and HSV2) based on a polymerase-chain-reaction screening of corneal scrapings. In addition, in vivo corneal confocal microscopy revealed focal areas of hyperreflective epithelial cells and hyperreflective subepithelial dendritic structures overlying activated keratocytes. All the patients improved with oral valacyclovir and topical steroids.

The authors conclude that archipelago keratitis appears to be a distinct form of recurrent herpetic epithelial keratitis, and that early diagnosis and quick administration of oral antiherpetic and topical anti-inflammatory therapy may prevent scarring.

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Aberrations and Depth of Focus in Aspheric and Spherical IOLs
November’s Ophthalmology

Rocha et al. conducted a randomized, prospective study to evaluate the relationship between spherical aberration and depth of focus in cataract patients implanted with aspheric and spherical IOLs. In this study, different IOL models (AcrySof IQ, AcrySof SN60AT and Sensar AR40) were implanted in 120 eyes of 60 patients with bilateral cataracts. The researchers analyzed pupil diameter under photopic, mesopic and scotopic conditions, and evaluated distance, intermediate and near visual acuities with distance correction. Wavefront analysis was performed 30 and 90 days following surgery.

The AcrySof SN60AT implant had higher values of spherical aberration and better distance-corrected near visual acuity. The AcrySof IQ group showed a lower induction of spherical aberration and worse distance-corrected near visual acuity.

The authors conclude that residual spherical aberration may improve depth of focus, while the tolerance to defocus seems to be higher in eyes implanted with spherical IOLs than in eyes implanted with aspheric IOLs.

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New Tumors in Retinoblastoma Despite Systemic Chemotherapy
November’s Ophthalmology

Wilson et al. have found that new tumors continue to form in patients with hereditary retinoblastoma despite treatment with primary systemic chemotherapy. The authors reviewed charts of 58 patients with hereditary retinoblastoma.

The authors found an overall cumulative incidence of 10 percent at two years following the start of chemotherapy—with 36 new tumors in 11 eyes. Of these, 17 percent were in the macula, 44 percent were in the midzone and 39 percent were in the periphery. Factors that significantly increased the likelihood of new tumor formation included younger age at diagnosis, a family history of retinoblastoma and a tumor’s Reese-Ellsworth classification. The authors noted that new tumor formation in retinoblastoma appears to be closely tied to retinal development. Thus, in theory, only therapies that specifically target retinal development could prevent new tumors from occurring.

Nevertheless, the authors conclude that systemic chemotherapy may impact the growth of small undetected lesions by slowing their growth and facilitating later focal consolidation.

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American Journal of Ophthalmology

Strabismus and Quality of Life in Adults
November’s AJO

With the intention of developing a health-related quality-of-life instrument, Hatt et al. conducted interviews to identify the specific concerns of adults with strabismus.

In this study, 30 adults with strabismus (17 with diplopia and 13 without) underwent individual interviews using 11 open-ended questions. The audiotaped transcripts were reviewed independently by three investigators. Phrases regarding how strabismus affected everyday life were grouped into topic areas and the frequency of each topic analyzed for subjects with and without diplopia. A total of 1,508 phrases were extracted, although 14 percent were excluded because they did not pertain to health-related quality of life. From the remaining 1,301 phrases, 48 topic areas were apparent.

For patients with diplopia, the most frequently occurring topics were nonspecific negative feeling (88 percent), general disability (88 percent) and driving (82 percent). In those without diplopia, the most frequently mentioned topics were appearance to others (92 percent) followed by problems with eye contact (77 percent) and interpersonal relationships (77 percent). Of the topics that were common to both groups, two of the most frequent were driving and nonspecific negative feeling.

There are many issues that negatively affect the quality of life in adults with strabismus. The frequency and type of concerns confirm the importance of health-related quality-of-life assessment as an important aspect of strabismus management.

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Contact Lens–Associated Microbial Keratitis
November’s AJO

Stapleton et al. evaluated the associations between disease severity, causative organism and climatic variation in contact lens–related microbial keratitis in Australia.

The researchers identified 236 patients with presumed contact lens– associated microbial keratitis lasting more than one year. Cases were graded for severity based on lesion size and location criteria. Causative organisms were assigned to environmental or endogenous groups. Climate and daytime temperature and humidity were also determined for the geographic location of each event.

Severe contact lens–related microbial keratitis was more likely to occur in warmer regions of the country (P < 0.001), compared with smaller, increasingly peripheral corneal lesions that were more common in areas with cooler conditions (P < 0.001). Culture-proven keratitis was predominantly caused by environmental organisms with Pseudomonas aeruginosa being recovered most frequently. Environmental organisms were isolated more commonly from tropical regions of the country and also accounted for nearly all cases of vision loss that occurred during the study period. Humidity did not have a significant effect on the causative organism.

Climatic conditions play a role in disease severity and causative organism in contact lens–related microbial keratitis. This is of special concern for practitioners involved in contact-lens care and contact-lens wearers who live in or travel to tropical areas.

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Visual Impairment in Children With Congenital Toxoplasmic Retinochoroiditis
November’s AJO

Tan et al. gathered information to assist parents of children with congenital toxoplasmosis regarding the long-term risk of visual impairment resulting from ocular toxoplasmosis.

Two hundred and eighty-one of 284 infected children who underwent ophthalmic examinations were followed up to a median age of 4.8 years. One in six children (17 percent) had at least one retinochoroidal lesion, and two-thirds of those had a lesion at the posterior pole. In 33 children with retinochoroiditis who had visual acuity measured after 3 years of age, 94 percent had normal vision in the best eye (6/12 Snellen or better), as did 91 percent of the 23 children with a posterior pole lesion. Analyses based on affected eyes showed that 42 percent had a posterior pole lesion, of which 52 percent had normal vision, as did 84 percent of eyes with a peripheral lesion alone. Vision predicted by the ophthalmologist was moderately sensitive (59 percent) but overestimated impairment associated with posterior pole lesions. Of 44 children with information on acuity, four (9 percent) had bilateral visual impairment worse than 6/12 Snellen.

Severe bilateral impairment occurred in 9 percent of children with congenital toxoplasmic retinochoroiditis. Half the children with a posterior pole lesion and one in six of those with peripheral lesions alone were visually impaired in the affected eye.

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Mitomycin C During LASEK as a Prophylaxis for Corneal Haze
November’s AJO

Thornton et al. evaluated the efficacy of low-dose (0.002 percent) mitomycin C (MMC) vs. no prophylactic MMC in reducing corneal haze after surface laser ablation. Ninety-two eyes with no MMC application and 83 eyes with 0.002 percent MMC application during laser epithelial keratomileusis (LASEK) were analyzed.

When subjected to univariate analysis, the no-dose MMC and low-dose MMC groups were statistically similar except for a thinner corneal pachymetry (P < 0.001), higher spherical equivalent error (P = 0.006) and smaller ablation zone (P = 0.009) in eyes not treated with MMC. Multivariate analysis was used to overcome the preoperative statistical differences between the two groups. Eyes treated with low-dose MMC demonstrated statistically less haze at all postoperative time points and in each myopic subgroup (P < 0.001). The postoperative uncorrected visual acuity and efficacy ratio, however, showed no difference between the groups, except for better efficacy ratio with MMC at one and two months.

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Archives of Ophthalmology

Laser Confocal Microscopy Findings in Three Types of Corneal Stromal Dystrophy
September’s Archives

Using in vivo laser confocal microscopy, Kobayashi et al. investigated corneal stromal dystrophies and their relationship to histopathology. Seven patients with Avellino corneal dystrophy, two patients with lattice corneal dystrophy and two patients with macular corneal dystrophy were examined genetically, by slit-lamp biomicroscopy, by in vivo laser confocal microscopy and histopathologically.

In Avellino dystrophy (R124H heterozygous missense mutation of the TGFBI gene), reflective granular materials with irregular edges were observed in the superficial stroma. In lattice corneal dystrophy (R124C and L527R heterozygous missense mutations of the TGFBI gene), reflective branching filaments of variable width were observed in the stroma. In macular corneal dystrophy (A217T homozygous missense mutation of the CHST6 gene), homogeneous reflective materials with dark striaelike images were observed throughout the stroma. All confocal findings correlated well with histopathological findings.

The authors conclude that in vivo laser confocal microscopy is capable of high-resolution visualization of characteristic corneal microstructural changes related to three types of genetically mapped corneal stromal dystrophy. Use of laser confocal microscopy may be valuable in differential diagnosis of corneal stromal dystrophies, especially when diagnosis is otherwise uncertain.

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Prediction of Visual Field Progression in Glaucoma
September’s Archives

Nouri-Mahdavi et al. evaluated the issue of visual field progression in glaucoma from a new perspective. They applied a predictive model to a subgroup of the longitudinal visual field series from 156 patients in the Advanced Glaucoma Intervention Study (AGIS) who were followed for eight years or longer.

They compared the performance of three commonly used techniques for prediction of visual field progression: pointwise linear regression analysis (PLR), Glaucoma Change Probability Analysis (GCPA), and the AGIS criteria. The visual field outcome at eight years for each method was considered the external standard against which the performance of each method over time was compared.

Visual field progression at eight years was detected in 35 percent, 31 percent and 22 percent of patients by PLR, GCPA and AGIS, respectively. The AGIS technique detected more progression during the first four years of follow-up than PLR or GCPA. PLR and GCPA had the highest concordance, but they agreed on the spatial distribution of progression in only one-third of test locations. Reversal of progression was rare when performance of methods at four and eight years was compared with a false positive detection rate at four years.
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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.
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THE YEAR IN REVIEW

The editors of the American Journal of Ophthalmology, Archives of Ophthalmology and Ophthalmology invite you to a review of interesting research published during the last year that has had immediate clinical relevance to the profession.

The Editors’ Choices Symposium
Monday, Nov. 12
Time: 8:30 to 10:30 a.m.
Room: La Nouvelle Orleans Ballroom C
Fee: No charge

EyeNet will publish a supplement to its January 2008 issue covering these Editors’ Choices papers.

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Roundup of Other Journals

Role of IGFNP3 and Vascular Regrowth in Retinopathy of Prematurity
Proceedings of the National Academy of Sciences
2007;104:10589–10594

Vessel loss that results in hypoxia induces retinal neovascularization in diabetic retinopathy and in ROP. Lofqvist et al. explain that insulinlike growth factor 1 (IGF1) is a key modulator of ROP and has been associated with diabetic retinopathy. Yet the role of IGF-binding protein-3 (IGFNP3) in angiogenesis in vivo has not yet been well understood. In this report, the researchers define IGFNP3 as a new modulator of vascular survival and regrowth in oxygen-induced retinopathy. Knowing how IGFNP3 modulates angiogenesis is vital because the IGF1/ IGFNP3 combination is now available clinically.

In a clinical study, the investigators measured IGFNP3 and IGF1 plasma levels weekly and examined retinas in premature infants at high risk for ROP born at gestational ages less than 32 weeks. The mean level of IGFNP3 for infants with proliferative ROP was 802 µg/l, and the mean level for infants with no ROP was 974 µg/l.

They conclude that IGFNP3, independent of IGF1, helps to prevent oxygen-induced vessel loss and to promote vascular regrowth, resulting in less retinal neovascularization.

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Early Screening of Ocular Disorders in Children With Down Syndrome
Developmental Medicine & Child Neurology
2007;49:513–515

In the United Kingdom, the Down Syndrome Medical Interest Group (DSMIG) created screening guidelines for ocular problems in children with Down syndrome. To determine the effectiveness of this effort, Stephen et al. reviewed surveillance of children with Down syndrome before and after these guidelines were implemented.

The researchers found that 34 of 36 children received a full ophthalmologic examination after the DSMIG protocol in the neonatal period, compared with nine of 27 children prior. Cataracts were discovered in three of 43 newborns after the new guidelines. Ocular disorders included strabismus, nasolacrimal duct obstruction, cataracts and nystagmus. Also, by age 5, 43 percent of children had a significant refractive error and required corrective lenses.

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DSAEK for Bullous Keratopathy and Fuchs’ Dystrophy
Cornea
2007;26:670–674

In a prospective, case series of 34 patients, Koenig et al. have found that Descemet’s stripping automated endothelial keratoplasty (DSAEK) for bullous keratopathy and Fuchs’ endothelial corneal dystrophy results in improved visual acuity with only a mild tendency toward hyperopic shift and without significant induced astigmatism six months following the procedure.

The average six-month postoperative best-corrected visual acuity was 20/42, with one patient achieving 20/20 vision. Patients who did not undergo simultaneous phacoemulsification and IOL implantation experienced a hyperopic shift in refraction of 1.19 ± 1.32 D. No statistically significant change was found in refractive astigmatism, topographic astigmatism or keratometry in the six-month period. The first half of patients undergoing the procedure experienced an average endothelial cell loss of 59 percent, in contrast with 41 percent in the second half of cases—a factor the authors said may be related to surgical experience. Postoperative complications were treatable and included donor lenticule dislocation, iatrogenic donor failure, endothelial graft rejection and pupillary block glaucoma.

They conclude that DSAEK provides six-month postoperative visual acuity comparable to that of deep lamellar endothelial keratoplasty and better than that of standard penetrating keratoplasty in patients with pseudophakic bullous keratopathy, Fuchs’ dystrophy and aphakic bullous keratopathy.

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Protecting Eyes While Administering Intraocular Injections
Retina
2007;27:609–612

Do physicians use eye protection when administering intraocular injections? Do they know the infection risk of eye splash events? Bourla et al. posed these questions to 40 retina fellows and 24 retina specialists in a survey.

They found that 25 percent of the fellows and 33.3 percent of the specialists used eye protection, including corrective glasses, during all intraocular injections. Two of the retina fellows and none of the specialists used special forms of eye protection. In addition, six fellows and two retina specialists reported 12 conjunctival or corneal splash occurrences. Eleven of these splash events were due to fluid reflux during the subconjunctival anesthetic injection, and one event occurred during an anterior chamber tap. Splash events were significantly more likely to be experienced by fellows, and most respondents were aware of the risk for transconjunctival viral infection.

While the authors acknowledge that the risk for eye splash while administering subconjunctival anesthetic before intraocular injections is relatively small, the rising seroprevalence of blood-borne viruses such as hepatitis B virus, hepatitis C virus and human immunodeficiency virus poses a threat. Indeed, even a small risk may lead to serious health concerns, which is why the authors recommend taking universal precautions.
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Roundup of Other Journals is written by Lori Baker Schena and edited by Deepak P. Edward, MD.

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