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Journal Highlights

New Findings from Ophthalmology, AJO and Archives
 
 

August’s Ophthalmology:

Scleral Buckling Is Comparable to Primary Vitrectomy in Pseudophakic and Aphakic Retinal Detachment

Semiautomated Kinetic Perimetry for Advanced Visual Field Loss

Laser Peripheral Iridotomy After Acute Primary Angle Closure Is Linked to Cataract Progression

Dragged-Fovea Diplopia Syndrome

Medicare Data Show an Increase in Endophthalmitis After Cataract Surgery Between 1994 and 2001

American Journal of Ophthalmology:

Perioperative Complications of Trabeculectomy

Use of OCT to Monitor PDT in AMD Patients

Archives of Ophthalmology:

A Population-Based Study on the Visual Outcome in 10-Year-Old Preterm and Full-Term Children

Delayed Visual Decline in Patients With “Stable” Optic Neuropathy

Blunt Trauma of the Aging Eye: Mechanisms of Injury and Increasing Lens Stiffness

Roundup of Other Journals:

Accuracy of IOL Calculations in Pediatric Cataract Surgery

A Safe Treatment for Actinic Keratosis—5 Percent Imiquimod Cream, Three Times Per Per Week

Using Virtual Reality Technology to Treat Amblyopia

Tonometers: Pascal vs. Goldmann


Previews

Scleral Buckling Is Comparable to Primary Vitrectomy in Pseudophakic and Aphakic Retinal Detachment
Ophthalmology
August's issue

In a prospective, randomized, multicenter clinical trial, Ahmadieh et al. demonstrated that scleral buckling and primary vitrectomy without an encircling band have comparable anatomic and visual results when treating pseudophakic and aphakic retinal detachment.

The study involved 225 eyes of 225 patients who were randomly assigned to one of these treatment approaches.

At the one-, two-, four- and six-month follow-up examinations, there were no statistically significant differences between the two groups with regard to the single operation retinal reattachment rate.

The authors report that proliferative vitreoretinopathy was the main cause of anatomic failure in both groups, occurring independently of the surgical technique used.

In light of these comparable findings, the authors conclude that surgeons may choose to base treatment strategy on such factors as patient compliance, cost of surgery, experience and capability of vitreoretinal surgeons, and availability of appropriate instrumentation.

Semiautomated Kinetic Perimetry for Advanced Visual Field Loss
Ophthalmology
August’s issue

For almost six decades, manual kinetic perimetry using a Goldmann perimeter has served as the standard to survey the extent and shape of profound visual field defects.

However, a new software-based technique called semiautomated kinetic perimetry addresses some of the disadvantages of Goldmann perimetry. The software performs interactive kinetic visual field examination (with the Octopus 101 instrument), using computer-controlled presentation of a stimulus at a specified constant velocity for any chosen Goldmann stimulus size and intensity. In this prospective case series, Nowomiejsk et al. compared the two techniques. They found that the isopter shape and size obtained with the semiautomated technique were very similar to those obtained on the same eyes with the manual technique. The semiautomated technique was preferred by 60 percent of patients with concentric constriction of the visual field.

The researchers conclude that semiautomated kinetic perimetry may prove advantageous in diagnosing and monitoring advanced visual field loss because it eliminates the examiner’s reaction time and provides quantitative assessment of the condition.

Laser Peripheral Iridotomy After Acute Primary Angle Closure Is Linked to Cataract Progression
Ophthalmology
August’s issue

Lim et al. have found that prophylactic laser peripheral iridotomy in fellow eyes of patients with acute primary angle closure is associated with a high rate of development of visually significant cataracts.

They studied 60 Asian patients with unilateral acute primary angle closure who underwent prophylactic LPI within one week of presentation.

Within 12 months, 14 of the 60 eyes showed significant cataract progression in any lens region. Progression in the nuclear, cortical and posterior subcapsular regions was documented in 5 percent, 6.7 percent and 16.7 percent of cases, respectively. The authors maintain that these are “alarmingly high rates of cataract progression” for a procedure that is universally regarded as relatively “harmless” and done prophylactically in many patients with narrow angles to prevent angle-closure glaucoma.

They conclude that performing LPI in eyes with asymptomatic narrow angles—without glaucomatous optic nerve damage, peripheral anterior synechiae or raised IOP—to prevent acute primary angle closure may cause more harm than good and should be considered carefully.  

Dragged-Fovea Diplopia Syndrome
Ophthalmology
Augusts’s issue

In an effort to diagnose and treat patients with dragged-fovea diplopia syndrome more effectively, De Pool et al. describe a simple diagnostic test and treatment option originating from a retrospective, observational case series of 95 eyes of 83 patients with the condition.

The researchers discovered a useful test for demonstrating the effects of peripheral vs. central fusion, called the “lights on-off” test, which involves the patient looking at a single white 20/70 letter on a black monitor screen.

With the room lights on, the single white letter is seen double in patients with this syndrome. When the room lights are turned off, the doubled letter becomes single within two to 10 seconds.

Their simple treatment option involved monocular occlusion with a piece of Scotch Satin tape.

The authors conclude that the test can accurately diagnose the syndrome early, thus helping patients avoid unnecessary prism glasses prescription and development of true strabismus secondary to the unnecessary prism.

Medicare Data Show an Increase in Endophthalmitis After Cataract Surgery Between 1994 and 2001
Ophthalmology
August’s issue

After conducting a population-based review of Medicare beneficiary claims data, West et al. found that the national rates of presumed endophthalmitis after cataract surgery increased substantially between 1994 and 2001.

Because of a lag in the availability of Medicare data, the authors cannot determine whether this rate has since stabilized or has continued to increase. Yet in 2001, approximately one in every 400 cataract surgeries appears to have been followed by an episode of endophthalmitis, and among patients 90 years and older, the rate approached one in 300. Rates of endophthalmitis adjusted for age, gender and race were significantly higher from 1998 to 2001 than in earlier years. In addition, older age and black race were associated with increased risk of endophthalmitis.

Since cataract surgery is such a common procedure, these findings should be of great concern to the medical community. The researchers call for risk factor studies that could then lead to specific interventions. This is especially crucial given the aging U.S. population.

Reviews

Perioperative Complications of Trabeculectomy
American Journal of Ophthalmology
July's Issue

The Collaborative Initial Glaucoma Treatment Study has generated a number of reports useful to clinicians. This latest one, written by Jampel and other members of the CIGTS Group, describes the incidence of and risk factors for surgical complications reported during trabeculectomy and within the first postoperative month.

The data were collected prospectively in a multicenter randomized clinical trial. The complications were tabulated for the 300 CIGTS patients randomized to surgery. Logistic regression analyses were used to identify risk factors for complications. Among the 300 patients randomized to initial surgery, 465 trabeculectomies were performed.

Intraoperative complications were reported in 55 eyes (12 percent). The most frequently reported complications were anterior chamber bleeding during surgery (8 percent) and conjunctival buttonhole (1 percent). Early postoperative complications were reported in 50 percent. Complications included shallow or flat anterior chamber (13 percent), encapsulated bleb (12 percent), ptosis (12 percent), serous choroidal detachment (11 percent) and anterior chamber bleeding or hyphema (10 percent). There were three localized suprachoroidal hemorrhages (0.7 percent) and no cases of endophthalmitis.

Older patients were more likely to experience serous choroidal detachment, new anterior or posterior synechiae, and wound leak. Black patients were less likely to experience anterior chamber bleeding, but more likely to experience postoperative ptosis. The number of subjects who experienced bilateral complications was higher than that which would have been predicted by chance alone.

The incidence of transient and self-limiting complications was high in the perioperative period, but there seemed to be few complications with the potential to cause severe, sustained vision loss.

Use of OCT to Monitor PDT in AMD Patients
American Journal of Ophthalmology

July's Issue

Optical coherence tomography is being used as a diagnostic and monitoring device for several ocular diseases.

Salinas-Alaman et al. evaluated the role of OCT in determining choroidal neovascularization activity before and after photodynamic therapy in patients with age-related macular degeneration.

In this institutional prospective observational case study, 53 patients (62 eyes) with AMD were observed for the presence or absence of leakage on fluorescein angiography, presence of intraretinal or subretinal fluid on OCT, and macular and choroidal neovascular complex thickness on OCT.

The study found that the macular thickness decreased significantly after PDT. However, no significant changes in CNV thickness were measured after PDT. Once the diagnosis of AMD was established before treatment, OCT had a sensitivity of 96.8 percent for detecting CNV activity. After treatment, OCT had a good sensitivity (95.6 percent) and a moderate specificity (59 percent) in determining CNV activity, which resulted in a diagnostic efficiency (proportion of correct results) of 82.9 percent.

The study shows that OCT appears to be useful for indicating CNV activity and may serve as a complementary technique for deciding the need for PDT and re-treatment in patients with AMD.

A Population-Based Study on the Visual Outcome in 10-Year-Old Preterm and Full-Term Children
Archives of Ophthalmology
2005;123:825–832

Larsson et al. evaluated the visual outcome in 216 ten-year-old prematurely born children who had previously been included in a population-based study on the incidence of retinopathy. The researchers then compared their outcome with the results of 217 full-term controls. Distance and near visual acuity were assessed with linear letter logMAR charts.

They found that prematurely born children had reduced distance and near visual acuity as compared with full-term children, even when children with ROP and neurological disorders were excluded. Children who had been treated with cryotherapy had the highest risk of a reduced visual acuity. Two percent of the prematurely born children were visually impaired.

Delayed Visual Decline in Patients With “Stable” Optic Neuropathy
Archives of Ophthalmology
2005;123:785–788

Kim et al. describe the clinical course of three patients who experienced slowly progressive visual loss in adulthood after suffering childhood optic nerve injury.

All three patients had a monophasic illness in childhood that caused bilateral optic atrophy and visual impairment. Following decades of stability, each suffered a gradual, symptomatic visual decline that extended over years.

The authors hypothesize that the late visual decline in these three patients resulted from deleterious effects of age-related axonal loss on an already depleted population of neurons.

Blunt Trauma of the Aging Eye: Mechanisms of Injury and Increasing Lens Stiffness
Archives of Ophthalmology
2005;123:789–794

In this study by Sitzel et al., a validated computational model of the eye incorporating fluid and solid components was altered to include heightened lens stiffness with advanced age.

The model’s response to impacts from a foam particle, steering wheel and an air bag indicated that peak stresses in the posterior portion of the ciliary body increased with increasing lens stiffness. Also, there was a concurrent decrease in peak stress in the posterior portion of the zonules. This effect was most pronounced for the two most severe impact types—those of the air bag and steering wheel. Lens stiffness did not significantly affect stresses in the corneoscleral shell, suggesting there is little effect on the probability of globe rupture due to lens stiffness changes alone.

In summary, these data suggest that trauma to the lens, ciliary body and zonules may be related to increased stiffness of the lens.The elderly eye may be more susceptible to ciliary body– related eye injuries in traumatic impact scenarios.

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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. Read Ophthalmology and AJO articles in full at www.ophsource.com; Archives articles at archopht.ama-assn.org.

Roundup of Other Journals

Accuracy of IOL Calculations in Pediatric Cataract Surgery
Journal of the American Association for Pediatric Ophthalmology and Strabismus
2005;9:160–165

Compared with adult eyes, children’s eyes have smaller axial lengths, smaller, steeper corneas, shallower anterior chambers and disproportionately smaller posterior segment/axial length ratios. Yet despite these differences, most IOL formulas used in children undergoing cataract surgery incorporate normal adult parameters.

Consequently, the accuracy of these procedures may be suspect. And, in fact, Neely et al. found that the accuracy of commonly used IOL calculation formulas was generally reasonable but highly variable within the pediatric population.

The authors reviewed 101 consecutive cases to ascertain the predictability of desired refractive outcomes immediately following pediatric cataract surgery. They compared several commonly used IOL calculation formulas, including the SRK II, SRK T, Hoffer Q and Holladay I.

They found that 23 percent of the pediatric patients had a refractive outcome more than 2 D from the anticipated result. The variability of refractive outcomes was particularly evident in children younger than age 2, and in those with axial lengths less than 19 millimeters. These findings lend support for the development of a new IOL calculation formula specially designed for pediatric patients.

A Safe Treatment for Actinic Keratosis—5 Percent Imiquimod Cream, Three Times Per Per Week
Archives of Dermatology
2005;141:467–473

Actinic keratoses are epidermal lesions that occur in fair-skinned individuals after long-term exposure to ultraviolet radiation.

Korman et al. found that dosing with 5 percent imiquimod cream three times per week for 16 weeks was a safe and effective treatment for AK.

Currently, AK is treated with cryosurgery, curettage with or without electrosurgery and topical fluorouracil. However, none of these target a critical component of the disease—the suppression of the immune response.

Imiquimod induces the production of interferon alpha, tumor necrosis factor alpha, and interleukin 12, with a resulting cytokine cascade that may induce and/or support a cytotoxic T-lymphocyte immune response.

Two Phase 3 randomized, double-blinded studies were conducted on 492 patients 18 years or older with four to eight AK lesions. Complete and partial clearance rates for the imiquimod-treated patients were significantly higher than the vehicle-treated patients. While overall efficacy was higher for dosing three times per week rather than for two times per week, the rate of local skin reactions was also higher.

The authors conclude that dosing with imiquimod is effective, and could be tailored to minimize drug exposure and adverse effects.



Using Virtual Reality Technology to Treat Amblyopia
Eye
Advance Online Publication, April 15, 2005;
doi:10.1038/sj.eye.6701882
(Go to
www.nature.com/eye and search for “eye.6701882”)

Eastgate et al. report on a treatment approach to amblyopia designed as an alternative to patching.

The authors, a collaborative group of ophthalmologists at Queen’s Medical Centre, Nottingham, England, and the Virtual Reality Applications Research Team based at the University of Nottingham, have produced a prototype Interactive Binocular Treatment System.

This system incorporates adapted virtual-reality technology and specially written software that encourages the two eyes to work together to assimilate two separate images into a coherent image. Interactive 2-D and 3-D games and videos are presented via a binocular display for the patient, and a control screen for the clinician.

Early case studies suggest promising results in children for whom previous amblyopia treatments proved unsuccessful. The strengths of the system are that it is interactive and can be adapted to suit the ability and needs of the patient. Furthermore, since it involves video games, the treatment can be made “captivating and enjoyable”—a far cry from patching.

The authors conclude that the system is only in its initial phases, and further research is needed to determine the efficacy of this new approach.

Tonometers: Pascal vs. Goldmann
Eye
Advance Online Publication, April 1, 2005;
doi:10.1038/sj.eye.6701849
(Go to
www.nature.com/eye and search for "eye.6701849")

In a prospective, comparative case series, Ku et al. compared IOP measurements obtained using the Pascal dynamic contour tonometer with those obtained using the standard Goldmann applanation tonometer, and correlated those measurements with central corneal thickness in 106 glaucoma patients with normal corneas.

They found that IOP measured by the two instruments correlated significantly, though the Pascal measurements were slightly higher than those of the Goldmann tonometer. However, while IOP measured by the Goldmann tonometer correlated strongly with CCT, the relationship between IOP measured by the Pascal tonometer and CCT approached significance. The differences between Goldmann tonometer- and Pascal tonometer-measured IOP also correlated strongly with CCT.

The researchers conclude that since Pascal tonometer IOP measurements demonstrated relative independence from CCT, the Pascal tonometer has a potential clinical role for patients with CCT outside the normal range.


Roundup is written by Lori Baker Schena and edited by Deepak P. Edward, MD.