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January 2006

 
Journal Highlights

New Findings from Ophthalmology, AJO and Archives
 
 

February’s Ophthalmology:
• No Association Seen Between Apolipoprotein E Gene and Early Age-Related Maculopathy
• Medicare Data Show Uveitis in the Elderly More Prevalent Than Previously Thought
• Multifocal Visual Evoked Potential a Sensitive, Specific Tool for Detecting Optic Neuritis

January’s Ophthalmology:
• Improvised Explosives Most Common Cause of Eye Injury During Iraq Insurgency
• Verteporfin PDT With Triamcinolone Improves Acuity in AMD Neovascularization
• Lateral Tarsal Strip and Everting Sutures for Involutional Entropion Can Be Performed by General Ophthalmologists
• Acanthamoeba Shows Affinity for First-Generation Silicone Hydrogel Contact Lenses

January's American Journal of Ophthalmology:
• Retinal Nerve Fiber Thickness vs. Optic Disc Algorithms for Detecting Glaucoma
• Categorizing the Stage of Glaucoma From Prediagnosis to End-Stage Disease
• Three Methods of Measuring Corneal Thickness and Anterior Chamber Depth

December's American Journal of Ophthalmology
• Tissue Adhesive Effective for Sealing Clear Corneal Cataract Wounds
• Recovery of Corneal Subbasal Nerve Density After PRK and LASIK
• Pediatric Amblyopia Risk Investigation Study
• Choroidal Biopsies for Intraocular Tumors of Indeterminate Origin

November’s Archives of Ophthalmology:
• Tissue Engineering for Glaucoma
• The Effect of Physician Reimbursement on the Rate and Cost of Cataract Surgery
• Treatment of Retinal Angiomatous Proliferation in AMD

Roundup of Other Journals:
• Central Corneal Thickness Highly Heritable
• Stem Cells for Human Corneal Endothelium
• Serum Inflammatory Markers in Diabetic Retinopathy
• Coffee No, Neckties Yes for Glaucoma Patients



Previews

No Association Seen Between Apolipoprotein E Gene and Early Age-Related Maculopathy
Ophthalmology
February’s issue

The apolipoprotein E (APOE) gene has been shown to influence lipoprotein metabolism and is linked to neurodegenerative disorders such as Alzheimer’s disease. While an association between the APOE gene and age-related maculopathy (ARM) has been hypothesized, Wong et al. did not find evidence of a strong relationship in the Atherosclerosis Risk in Communities Study.

This population-based, cross-sectional study involved 10,139 middle-aged men and women of white and African-American ethnicity living in Forsyth County, N.C., Jackson, Miss., the suburbs of Minneapolis, Minn., and Washington County, Md. The researchers found no evidence of a strong association between APOE and early ARM, even after controlling for age, gender, race and cigarette smoking.

They caution that the study population was relatively young and the prevalence of early ARM was only 5 percent. Consequently, they cannot exclude the possibility of a weaker association or that APOE may only influence the development of late ARM in older populations.

Medicare Data Show Uveitis in the Elderly More Prevalent Than Previously Thought
Ophthalmology
February’s issue

Uveitis in the elderly is more prevalent than previously thought, according to a Medicare cohort study by Reeves et al. The researchers studied data from a cohort of 21,644 Medicare beneficiaries drawn from the National Long-Term Care survey, a random sample of adults 65 years and older followed from 1991 through 1999.

The yearly uveitis incidence in this cohort averaged about 341 cases per 100,000. Anterior uveitis accounted for the majority of cases. The authors noted that the cohort experienced an almost 2 1/2-fold increase in uveitis prevalence, from 511 cases per 100,000 to 1,231 cases per 100,000 over the time period of the study, suggesting that the elderly can expect a marked increase in the burden of uveitis as the population ages.

Finally, this study demonstrated that Medicare claims data may represent a rich source of information, serving as a useful and cost-effective tool for monitoring uncommon diseases.

Multifocal Visual Evoked Potential a Sensitive, Specific Tool for Detecting Optic Neuritis
Ophthalmology
February’s issue

Multifocal visual evoked potentials (mVEP) is a method to diagnose optic pathway conditions by assessing visual evoked potentials as responses from multiple individual segments of the field of vision, allowing for objective information about amplitude to be combined with information on latency.

Fraser et al. conducted a cross-sectional study to determine if mVEP can detect evidence of optic neuritis (ON) and whether the results can differentiate between ON as a manifestation of multiple sclerosis (MS) and purely inflammatory ON.

The authors found that not only was mVEP a sensitive and specific tool for detecting optic neuritis, but there existed a significant difference in latency analysis findings between patient groups classified according to the McDonald MS criteria.

They conclude that if this latency pattern does reflect future clinical course, then the mVEP could provide a means of identifying those with a greater risk of future MS in the early post-acute stage of ON from those with white matter changes on MRI, thus helping physicians to determine optimal treatment strategies.

Reviews

Improvised Explosives Most Common Cause of Eye Injury During Iraq Insurgency
Ophthalmology
January's issue

During an Iraqi insurgency from January to September 2004, improvised explosive devices (IEDs) were the most common cause of ocular and adnexal injuries treated at the 31st Combat Support Hospital in Baghdad, Iraq.

In the prospective, hospital-based, observational analysis by Mader et al., 207 patients experienced severe ocular and adnexal injuries, including 132 open globes. The IEDs discussed were remotely controlled devices incorporating scavenged high-explosive artillery rounds, mortar rounds and plastic explosives. Ocular injuries created by IEDs commonly had avulsed portions of sclera or cornea, and the wound edges were ragged and difficult to repair. Secondary projectiles such as rock and dirt complicated surgical management. The authors commented that the close collaboration of the entire head and neck team in treating these patients greatly enhanced the ability to provide timely, high-quality surgical care to severely wounded patients. They noted that more consistent use of polycarbonate ballistic protective eyewear would have prevented some of the injuries reported.

Verteporfin PDT With Triamcinolone Improves Acuity in AMD Neovascularization
Ophthalmology
January's issue

Augustin and Schmidt-Erfurth report that verteporfin photodynamic therapy combined with intravitreal triamcinolone may improve the outcome of standard verteporfin PDT therapy in patients with choroidal neovascularization secondary to age-related macular degeneration.

The prospective, noncomparative case series involved 184 eyes of 184 patients with subfoveal, juxtafoveal and extrafoveal choroidal neovascularization. Sixteen hours after undergoing standard verteporfin PDT, patients received an intravitreal injection of 25 milligrams of triamcinolone—a procedure repeated at the three-month follow-up visit, when necessary. Visual acuity improved in the majority of patients by a mean increase of 1.22 Snellen lines, and the mean number of required treatments was 1.21.

The authors note that while verteporfin PDT alone effectively treats CNV secondary to AMD, re-treatments have been documented to be as high as 5.6 over two years. In contrast, the therapeutic approach in this study resulted in lower than anticipated re-treatment rates—justifying a randomized controlled trial to confirm these findings.

Lateral Tarsal Strip and Everting Sutures for Involutional Entropion Can Be Performed by General Ophthalmologists
Ophthalmology
January’s issue

Involutional entropion is a common eyelid malposition in the elderly caused by progressive attenuation of the lower lid soft tissue with horizontal and vertical laxity and enophthalmos.

Barnes et al. describe a solution involving a lateral tarsal strip and everting sutures (LTS+ES). In this approach, a standard lateral tarsal strip was created via a 10-millimeter lateral canthotomy incision and fashioned to an appropriate length to correct the horizontal lid laxity. A double-ended 5.0 nonabsorbable suture was placed through the strip. Four 6.0 Vicryl everting sutures were sited in the lateral two-thirds of the lower eyelid, and the lateral tarsal strip was secured inside the lateral orbital rim before tightening the everting sutures. The lateral canthotomy was closed in two layers.

Ophthalmic plastic surgeons and trainees performed this procedure, and 53 of 54 eyelids had a successful outcome with no recurrence by 18 months. The authors conclude LTS+ES is a good option for involutional entropion repair for the general ophthalmologist.

Acanthamoeba Shows Affinity for First-Generation Silicone Hydrogel Contact Lenses
Ophthalmology
January's issue

Two brands of silicone hydrogel (S-H) lens were introduced in the late 1990s: the PureVision lens, composed of balafilcon A, and the Focus Night & Day lens, composed of lotrafilcon A. Recently, Acuvue Advance, a “second-generation” S-H lens composed of galyfilcon A, was introduced.

Beattie et al. incubated unworn, worn and Pseudomonas aeruginosa biofilm-coated first- and second-generation S-H and conventional hydrogel lenses for 90 minutes in suspensions of plate-cultured Acanthamoeba castellanii trophozoites. Acanthamoeba demonstrated a greater affinity for the first-generation S-H lenses compared with the second-generation S-H and the conventional hydrogel lenses.

Prospective studies are needed to determine if these findings are of clinical significance since only one suspected case of Acanthamoeba has been reported in more than one
million global patient years of wear.

Retinal Nerve Fiber Thickness vs. Optic Disc Algorithms for Detecting Glaucoma
American Journal of Ophthalmology
January’s issue

The early detection of glaucoma would result in better preservation of visual field in most patients. Manassakorn et al. compared the performance of the retinal nerve fiber layer (RNFL) thickness and optic disc algorithms as determined by optical coherence tomography (OCT) to detect glaucoma in an observational cross-sectional study at an academic tertiary-care center.

The authors considered one eye from each of 42 control subjects and 65 patients with open-angle glaucoma with visual acuity of > 20/40, and no other ocular pathologic condition was selected.

Two OCT algorithms were used: “fast RNFL thickness” and “fast optic disc.” Area under the receiver operating characteristic curves and sensitivities at fixed specificities were determined. Discriminating ability of the average RNFL thickness and RNFL thickness in clock-hour sectors and quadrants was compared with the parameters that were derived from the fast optic disc algorithm. Classification and regression trees were used to determine the best combination of parameters for the detection of glaucoma.

The average visual field mean deviation was 0.0 and –5.3 decibels in the control and glaucoma groups, respectively. The RNFL thickness at the 7 o’clock sector, inferior quadrant, and the vertical cup/diopter ratio had the highest area under the receiver operating characteristic curves. At 90 percent specificity, the best sensitivities from each algorithm were 86 percent for RNFL thickness at the 7 o’clock sector and 79 percent for horizontal integrated rim width (estimated rim area). The combination of inferior quadrant RNFL thickness and vertical cup/diopter ratio achieved the best classification (misclassification rate, 6.2 percent).

The fast optic disc algorithm performed as well as the fast RNFL thickness algorithm for discrimination of glaucoma from normal eyes. A combination of the two algorithms may provide enhanced diagnostic performance.

Categorizing the Stage of Glaucoma From Prediagnosis to End-Stage Disease
American Journal of Ophthalmology
January’s issue

A staging system for glaucoma would lead to improved communication with researchers and patients. Mills et al. have tried to provide a reliable, comprehensive staging system to assess glaucoma stage on the basis of visual field results in the absence of any previous universally accepted glaucoma staging system (GSS).

The authors conducted a review of the published GSSs. The Bascom Palmer (Hodapp-Anderson-Parrish) system was selected as an appropriate platform for a retrospective GSS on the basis of visual fields. A panel of glaucoma specialists modified that system to cover the full range of disease progression, from preglaucoma diagnosis to complete blindness. The resulting GSS comprises six ordered stages based on the Humphrey visual field.

A review of patient charts from 12 U.S. glaucoma centers validated the modified GSS. These authors conclude that this GSS allows accurate staging of 100 percent of glaucomatous eyes on the basis of visual fields and other data, enabling evaluation of disease progression and resource utilization at various glaucoma stages. The treatment costs may be assigned to determine cost-effectiveness of treatment. Research utilizing the GSS found that cost of care increases with increasing disease severity. The GSS may be used as the basis for creating treatment guidelines, which have the potential to delay glaucoma progression and lower treatment costs.

Three Methods of Measuring Corneal Thickness and Anterior Chamber Depth
American Journal of Ophthalmology
January’s Issue

Accurate measurement of corneal thickness and anterior chamber depth enhances the evaluation and treatment of many disease processes or procedures. Buehl et al. compared three different methods of measuring corneal thickness (CT) and anterior chamber depth (ACD) in a prospective clinical trial.

Central corneal thickness (CCT), CT at four peripheral points, and central ACD were measured in 88 eyes of 44 healthy subjects with the Pentacam (rotating Scheimpflug camera; Oculus), Orbscan I (scanning slit topography system; Orbtek), and ACMaster (partial coherence interferometry; Carl Zeiss Meditec).

The upper (lower) limits of agreement for CCT measurements were 7.9 micrometers between ACMaster and Pentacam, 17.6 µm between ACMaster and Orbscan, and 25.2 µm between Pentacam and Orbscan. Correlation was high between all three methods. The upper and lower limits of agreement for ACD were 0.174 millimeters between ACMaster and Pentacam, 0.406 mm between ACMaster and Orbscan, and 0.384 mm between Pentacam and Orbscan. Correlation was high between the three methods. Correlation was lower for the CT measurements at the four peripheral points.

The CCT and ACD values obtained by Pentacam, Orbscan and ACMaster measurements correlated well and showed few outliers. The two new systems—Pentacam and ACMaster—seem to provide a reliable, easy-to-use, noncontact method of measuring CCT and ACD. Larger differences occurred only when measuring peripheral CT values, especially between ACMaster and the other two methods.

Tissue Adhesive Effective for Sealing Clear Corneal Cataract Wounds
American Journal of Ophthalmology
December’s Issue

Clear corneal cataract wounds have come under scrutiny because of possible higher rates of endophthalmitis compared with scleral wounds. Ritterband et al. evaluated the efficacy of a tissue adhesive (2-octyl cyanoacrylate with parabens) in sealing clear corneal cataract wounds in a laboratory investigation.

Seven human donor globes were prepared for Miyake video microscopy. A 3-millimeter clear corneal incision was created. A transscleral cannula was inserted and connected to a bottle of saline. The bottle height was varied to alter IOP. Droplets of India ink were placed on the wound. Main outcome measure was any influx of India ink into the anterior chamber as viewed through the Miyake system with IOP fluctuation or with manual pressure. If India ink was present in the eye, it was irrigated out, and the experiment was repeated with IOP fluctuation and manual pressure after the application of 2-octyl cyanoacrylate to the wound.

One eye demonstrated the presence of India ink inside the eye on IOP reduction to < 5 mmHg. Three eyes demonstrated the presence of India ink inside the eye with manual pressure. Three eyes did not leak with manual pressure or IOP variation. All seven eyes without glue leaked with exaggerated manual pressure at the wound edge. Of the seven eyes with tissue adhesive, none demonstrated influx of India ink with IOP variation or manual wound manipulation.

This laboratory model demonstrates that 2-octyl cyanoacrylate prevents the influx of ocular surface fluid independent of IOP and manual wound manipulation. This adhesive barrier substance may have future clinical uses.

Recovery of Corneal Subbasal Nerve Density After PRK and LASIK
American Journal of Ophthalmology
December’s Issue

Severing the corneal nerves during refractive surgery may have short- or long-term effects on the health of the cornea. Erie et al. measured and compared the return of corneal innervation up to five years after PRK and LASIK in a prospective, nonrandomized clinical trial.

Eighteen eyes of 12 patients received PRK to correct a mean refractive error of –3.73, and 16 eyes of 11 patients received LASIK to correct a mean refractive error of –6.56. Corneas were examined by confocal microscopy before and at one, two, three and five years after the procedures. Subbasal nerve fiber bundles were measured to determine density (visible length of nerve/frame area) and were expressed as micrometers
per square millimeter.

After PRK, mean subbasal nerve density was reduced by 59 percent at one year when compared with preoperative density. By two years, subbasal nerve density was not significantly different from density before PRK and remained unchanged to five years. After LASIK, subbasal nerve density was reduced by 51 percent, 35 percent and 34 percent at one, two and three years, respectively. By five years, subbasal nerves had returned to densities that were not significantly different from densities before LASIK.

Corneal subbasal nerve density does not seem to recover to near-preoperative densities until five years after LASIK, as compared with two years after PRK.


Pediatric Amblyopia Risk Investigation Study
American Journal of Ophthalmology
December’s Issue

Savage et al. assessed the learning curve, testability and reliability of vision screening modalities administered by pediatric health extenders in a prospective masked clinical trial.

Two hundred subjects from ages 3 to 6 underwent timed screening for amblyopia by physician extenders, who used the Lea Symbols Visual Acuity Test, the Random Dot E Stereoacuity Test (RDE), and noncycloplegic autorefraction (NCAR). Patients returned for a comprehensive diagnostic eye examination performed by an ophthalmologist or optometrist.

Average screening time was 5.4 minutes by Lea, 1.9 minutes by RDE and 1.7 minutes by NCAR. Test time for NCAR and RDE fell by 40 percent during the study period. Overall testability was 92 percent by Lea, 96 percent by RDE and 94 percent by NCAR.

Testability among 3-year-olds was 73 percent by Lea, 96 percent by RDE and 89 percent by NCAR. Reliability of Lea was moderate. Reliability of NCAR was high for astigmatism, moderate for spherical equivalent, and low for anisometropia.

Correlation of NCAR with gold standard cycloplegic retinoscopic refraction was very high for spherical equivalent and cylinder, and moderate for anisometropia.

With NCAR, physician extenders can quickly and reliably detect astigmatism and spherical refractive error in one-third the time it takes to obtain visual acuity. Lea has a lower initial cost but is time-consuming, only moderately reliable and more difficult for 3-year-olds than older children. Shorter examination time and higher reliability may make NCAR a more efficient screening tool for refractive amblyopia in younger children.

The sensitivity and specificity of NCAR and other screening methods in detecting amblyopia and its risk factors need further evaluation.


Choroidal Biopsies for Intraocular Tumors of Indeterminate Origin
American Journal of Ophthalmology
December’s Issue

Choroidal tumors of indeterminate origin remain a vexing problem for ophthalmologists. Kvanta et al. evaluated the role of pars plana, vitrectomy-assisted incisional biopsies in the management of choroidal tumors of unclear origin in a retrospective, noncomparative, consecutive interventional case series.

Ten consecutive patients with indeterminate choroidal tumors underwent a standardized three-port, pars-plana, vitrectomy-assisted subretinal biopsy using a bimanual approach with standard intraocular forceps and a diamond knife. Specimens were subjected to histopathological and immunohistochemical analyses.

A histologic diagnosis was obtained in all (10 of 10) cases, including choroidal melanoma (five of 10), metastasis (two of 10), subretinal hemorrhage (two of 10) and nodular scleritis (one of 10). Five eyes were enucleated as a result of the diagnosis. Three cases of postoperative complications were seen in three patients (rhegmatogenous retinal detachment, increased serous retinal detachment and vitreous hemorrhage). No cases of intra- or extraocular tumor spread were detected through follow-up periods ranging from three to 29 months.

The authors conclude that pars plana vitrectomy-assisted incisional biopsy is a valuable diagnostic procedure for cases of choroidal tumors of unknown origin, but they caution that postoperative complications and the potential risk of dissemination of tumor cells underscores rigorous case selection.

Tissue Engineering for Glaucoma
Archives of Ophthalmology
November’s Issue

Young et al., in a special article arising from The Glaucoma Foundation’s 10th Annual International Think Tank, report on recent advances in the field of tissue engineering and suggest ways in which these techniques can be applied to treat or prevent glaucoma and other optic neuropathies.

The prototypical “engineered tissue” consists of a scaffold and a population of cells. The scaffold may be natural, such as amniotic membrane, but more typically it is a biodegradable polymer constructed in a laboratory. The cell population is usually a stem or progenitor cell derived from embryonic stem cells or from the tissue that is being generated. The goal of this strategy is to generate normal tissue de novo for use in cell-based therapies.

Perhaps the most critical issue that must be addressed is biocompatibility. The eye has several unique microenvironments, and any tissue engineering construct must be compatible with these niches. Other issues such as the optimal type of scaffold and the cell source must also be solved before this important new technology can be used in the context of optic nerve disease.

We conclude that controlled drug delivery is the most realistic area to apply tissue engineering technology. Tissue engineering of the trabecular meshwork, optic nerve and retinal ganglion cells remain targets of future research. While the challenges of treating optic nerve disease are daunting, progress in tissue engineering, and the related field of regenerative medicine, are providing the tools to contemplate what seemed only a few years ago to be impossible.

The Effect of Physician Reimbursement on the Rate and Cost of Cataract Surgery
Archives of Ophthalmology
November’s Issue

Shrank et al. compared the effects of two reimbursement methodologies, fee-for-service (FFS) and contact capitation (CC), on cataract extraction rates and costs. 

A pre- and postanalysis of claims and encounter data for an average of 91,473 commercial beneficiaries and 14,084 Medicare beneficiaries receiving eye care from a network of ophthalmologists and optometrists was performed. The rate of cataract extractions per 1,000 beneficiaries, the costs of cataract procedures, the rates of noncataract procedures and the level of professional reimbursement for providers were compared during the final six months of FFS physician reimbursement and the first six months of CC. 

Both commercial and Medicare beneficiaries were approximately one-half as likely to have cataract extraction (P < 0.001) under CC compared with FFS. Professional reimbursement increased by 8 percent, while facility fees for cataract decreased by approximately 45 percent. Cataract surgical rates were disproportionately affected when compared with other ophthalmologic procedures. 

The authors conclude that CC reimbursement was associated with significant decreases in cataract extraction rates and costs compared with FFS. The frequency of cataract extraction surgery, the most common major elective procedure in ophthalmology, was more responsive to physician financial incentives than other ophthalmologic procedures. 

Treatment of Retinal Angiomatous Proliferation in AMD
Archives of Ophthalmology
November’s Issue

Bottoni et al. retrospectively reviewed consecutive patients with age-related macular degeneration who were diagnosed with and underwent treatment for retinal angiomatous proliferation (RAP). Multiple different treatment modalities were employed for the various stages of RAP and the outcome results assessed by the criteria of visual acuity change and anatomic closure of the lesion.

Eighty-one patients (99 eyes) with 104 RAPs were identified from Jan. 1, 2000, to Jan. 31, 2003. Forty-two lesions were at stage I, 42 at stage II and 20 at stage III. The following five treatments were performed: direct laser photocoagulation of the vascular lesion, laser photocoagulation of the feeder retinal arteriole, scatter “gridlike” laser photocoagulation, photodynamic therapy and transpupillary thermotherapy.

Complete obliteration of RAP was achieved in about 24 (57 percent) of the stage I lesions (with direct laser photocoagulation of the vascular lesion providing a 73 percent success rate and photodynamic therapy 45 percent), 11 (26 percent) of the stage II lesions (with scatter gridlike laser photocoagulation offering a 38 percent success rate and direct laser photocoagulation of the vascular lesion 17 percent) and only three (15 percent) of stage III lesions (P = 0.001). Predictive factors with a significant effect on final visual acuity were initial visual acuity (P = 0.003) and early lesion stage (P = 0.044). Best final visual acuity was a mean of 0.41 with direct laser photocoagulation of the vascular lesion in stage I, and a mean of 0.39 with photodynamic therapy in stage I, with a mean decrease of 2.5 and 3 lines from baseline, respectively.

The authors conclude that treatment of RAP remains difficult. Early detection of the lesion and subsequent direct conventional laser photocoagulation seems to be associated with better anatomical and functional outcome. Once the vascular complex is well-established, anatomical closure is rarely achieved.

______________________________
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

Central Corneal Thickness Highly Heritable
Investigative Ophthalmology & Visual Science
2005;46:3718–3722

Given that central corneal thickness (CCT) may constitute a key factor in glaucoma diagnosis and management, Toh et al. conducted a classic twin study to determine the heritability of CCT, comparing the covariance of CCT between monozygotic (MZ) and dizygotic (DZ) twins.

The researchers recruited 256 twin pairs from Australia and the United Kingdom (131 MZ and 125 DZ) and conducted an extensive ophthalmic evaluation in which they measured CCT by ultrasound pachymetry. Their findings indicated that CCT was a highly heritable trait with a heritability of 0.95. Unique environmental effect contributed only 5 percent of the variance. There were no significant differences in CCT between male and female patients, nor between the U.K. and Australian groups. These preliminary data suggest that CCT may be more heritable than optic disc cup area (0.86) and IOP (0.7).

The researchers conclude these results may lead to the discovery of more glaucoma-related genes. Indeed, although the genes determining CCT in the normal population have not been identified, there are many potential candidate genes, including those associated with diseases with thick or thin CCT phenotypes.

Stem Cells for Human Corneal Endothelium
Molecular Vision
2005;11:816–824

While human corneal endothelial cells have a documented impaired ability to divide, both in vivo and in culture, recent discoveries indicate an increased endothelial cell population in the periphery of the human cornea that may indicate the existence of stemlike cells.

Whikehart et al. assayed human corneas with attached scleral rims for telomerase activity and bromodeoxyridine (BrdU) incorporation to determine the presence of a stemlike cell marker and replicative activity. The researchers found evidence of telomerase activity and BrdU-linked alkaline phosphatase activity staining, which suggested that cells in the corneal endothelium may be renewed by stemlike cells located in a niche at the posterior limbus.

With this mechanism, it may be possible to minimize loss of endothelial cells over a lifetime because of naturally occurring cell death. However, their report also showed an increased cell renewal after trauma, a phenomenon that can be halted by upregulated synthesis of transforming growth factor beta within a few days of the trauma.

Serum Inflammatory Markers in Diabetic Retinopathy
Investigative Ophthalmology & Visual Science
2005;46:4295–4301

A study by Meleth et al. looking at serum inflammatory markers suggests evidence to support the role of inflammation in the pathogenesis of diabetic retinopathy.

A variety of serum factors were examined in 93 participants. Stromal cell-derived factor-1alpha and (RANTES)/CCL5 were significantly elevated in patients with at least severe nonproliferative diabetic retinopathy compared with those with less severe diabetic retinopathy. Positive immunostaining was observed in the inner retina for monocyte chemoattractant protein-1/CCL2 and RANTES of the patient with diabetes. Staining was strongly positive throughout the diabetic retina for the intercellular adhesion molecule-1/CD54. In contrast, normal retinal tissues showed little reactivity.

The authors conclude that these findings point to the role chemokines, cytokines and cell adhesion molecules play in the development of diabetic retinopathy and serve as a potential risk assessment tool in this population. However, further studies are necessary to establish a conclusive link between these molecules and diabetic retinopathy.

Coffee No, Neckties Yes for Glaucoma Patients
Journal of Glaucoma
2005;14:504–507 and 2005;14:508–510

According to two reports in the Journal of Glaucoma, glaucoma patients may want to avoid caffeine but can wear a tight necktie without worrying about elevating IOP.  

The first report, by Shandrasekaran et al., used data from The Blue Mountain Eye Study, to examine a possible relationship between coffee or caffeine intake and IOP in 3,654 participants age 49 and older living west of Sydney, Australia.

The researchers found after multivariate adjustment that individuals with open-angle glaucoma who drank coffee regularly had a significantly higher mean IOP (19.63 mmHg) than participants who did not drink coffee regularly (16.84 mmHg). Similar findings held true for caffeine intake. However, no association was found between coffee or caffeine consumption and higher IOP in those with ocular hypertension or those without open-angle glaucoma.

In the second report by Talty and O’Brien, a prospective study of 18 normal and 19 primary open-angle glaucoma patients investigated the effect of tight neckties on IOP. Interestingly, while a significant increase in IOP (1.58 mmHg) was detected after three minutes of tight necktie wear in the glaucoma group, IOP decreased significantly (0.94 mmHg) after 12 further minutes of tight necktie wear. Given these findings, the authors concluded that necktie wear does not pose a health threat to glaucoma patients.



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