Issue 5, 2013

 


 

University of Houston, College of Optometry

  • hjhh
    Vol. 1, No. 5, 2013

    Editor’s note: This volume covers the topics of glaucoma, dry eye disease, anterior segment surgery, corneal disease and contact lenses. The hope is that this augments your education, clinical practice acumen and keeps you up-to-date on important topics concerning contact lenses and the anterior segment. We are striving to present, in a succinct and pithy format, important information that does not cut into your already busy schedule, delivering clinical nuggets for the benefit of all of your patients.

 

 

 

 

 

 

glGlaucoma

The News: Secondary glaucoma after pediatric cataract surgery

Its Implication: What factors might predict eventual problems?

Resende GM, Lupinacci APC, Arierta CEL and Costa VP. Central corneal thickness and intraocular pressure in children undergoing congenital cataract surgery: a prospective, longitudinal study. Br J Ophthalmol 96:1190-1194, 2012.

The prevalence of glaucoma in children after having congenital cataract surgery is highly variable in the literature. Some studies cite 5%–32%, while others report a prevalence of nearly 100%. The aim of the study was to investigate changes in postoperative central corneal thickness (CCT) and IOP.

The study evaluated 37 eyes of 26 children (15 aphakic eyes and 22 pseudophakic) and monitored them at 6, 12, 18, 24 and 36 months after cataract surgery. IOP was measured using a Goldmann tonometer; for uncooperative patients, a Perkins tonometer was used under general anesthesia. Corneal thickness measurements were conducted with an ultrasound pachymeter.

The data showed that aphakic eyes tended to be of a younger age (15.2 ± 32.0 months) when compared to pseudophakic eyes (71.5 ± 53.1 months). Overall, a higher CCT change was observed in children who underwent an aphakic procedure compared to older children with pseudophakic eyes (56.1 ± 46.9 µm versus 12.7 ± 38.4 µm). This increase is likely age-related since aphakic procedures are performed in younger patients. This difference was significant postoperatively except at 6 and 18 months.The mean IOP increased significantly in both groups (no significant difference between groups) from 12.1 ± 2.3 to 13.9 ± 2.9 mm Hg at the 36-month visit. In the aphakic group only, IOP was moderately correlated with CCT, suggesting that the raised IOP may be the result of an increase in corneal thickness.

Post-Script/Caveat:

  • One must remember that this was a small sample size and results may be different when a larger sample size is used or a meta-analysis is conducted using various studies.

 

  • The authors do not indicate how many patients under-went Perkins tonometry with anesthesia; consequently, confluence with Goldmann was not performed.

 

  • Interestingly, the male to female ratio was much higher for the aphakic than the pseudophakic group.

 

  • As mentioned by the authors, endothelial microscope was not performed to assess cellular quantity and quality as a precursor to any corneal thickness change.

The News: IOP and CCT

Its Implication: Factors influencing in a diverse young adult population.

Fern K, Manny R and Gwiazda J. Intraocular pressure and central corneal thickness in the COMET cohort. Optom Vis Sci 89:1225–1234, 2012.

In this study of 385 ethnically diverse young adults (mean age 20.3 years), blacks were found to have signifi-cantly thinner central corneal thicknesses (CCT) than whites, Hispanics and Asians, and higher IOPs than whites and Hispanics.

Moreover, investigators did not find a correlation between IOP and CCT with increasing amounts of myo-pia. The authors do, however, concede that IOP measures obtained in this study do not reflect diurnal or time-related variances.

Of additional interest, a positive correlation was dis-covered between increased CCT and axial length. These associations were found in subjects who reported wearing contact lenses either most or all of the time.

Although investigators cannot explain this relation-ship, they did not attribute it to edema secondary to contact lens wear since longer vitreous chamber depths were also observed, and these measures do not take into account corneal thickness changes.

Bausch + Lomb is pleased to support the development and distribution of the Contact Lens & Anterior Segment Update under the editorship of Dr. William Miller. CLASU has been a longstanding educational tool that benefited educators and students alike. Providing a summary of timely basic and clinical research that has been through the peer-previewed process will bring greater attention to ocular surface health topics in a useful format. Bausch + Lomb has generously provided an unrestricted educational grant to support this publication.

Contact Lens and Anterior Segment Update is published bimonthly by Anadem Publishing, Inc., 3620 N. High Street, Columbus, Ohio 43214, USA. © Copyright 2013 by Anadem Publishing, Inc. All rights reserved. Reproduction in any form, including photocopying, in whole or in part, without prior written permission, is prohibited by law.

Abstract Writers: Amber Gaume Giannoni, OD, Anita Ticak, OD, MS

Advisory Board: Jan Bergmanson, OD, PhD, Alison McDermott, PhD

The material in Contact Lens and Anterior Segment Update is presented to professionals for educational purposes and is based upon information from sources believed to be reliable. The opinions expressed in the articles summarized herein are those of the articles’ authors and are not to be construed as the opinions or recommendations of the publisher. The material presented is not meant to be, and should not be relied upon for, recommendations regarding diagnosis or treatment for any individual case.

 

Post-Script/Caveat:

  • This study represents a large, diverse subject popula-tion and thus provides important forewarnings for clinical care.

 

  • Contact lens specifics such as a subject’s lens mate-rial, modality, asphericity or multifocal type were not included in the article.

 

  • Increased IOP status was evident even in younger black subjects.

 

  • Thinned CCT may necessitate earlier anti-glaucoma intervention in black patients.

The News: Primary open angle glaucoma

Its Implication: What will the disease look like over the next several decades?

Vajaranant T, Wu S, Torres M, et al. The changing face of primary open-angle glaucoma in the United States: demographic and geographic changes from 2011 to 2050. Am J Ophthalmol 154:303–331, 2012.

This cross-sectional investigation to estimate future prevalence rates of primary open angle glaucoma (POAG) in the US was designed using current census data com-bined with carefully selected population-based studies.

Presently, the number of estimated POAG cases in the US is 2.71 million, with the largest demographic consist-ing of non-Hispanic white women. The authors expect this number to increase to 7.32 million by the year 2050.

Of further interest, they also propose a shift will occur in the largest demographic group to older (>70 years) Hispanic/Latino men and predict that the per capita bur-den of POAG will fall heaviest on the states of New Mexico, Texas and Florida.

Post-Script/Caveat:

  • This study suggests that essential POAG screening should occur in older, non-Hispanic women and Hispanic/Latino men.

 

  • Cost effective POAG screening should target states such as New Mexico, Texas and Florida.

 

  • Studies such as this may influence future preventive healthcare policies.

dryDry Eye Disease

The News: Blepharitis and MGD

Its Implication: Successful treatment strategies.

Guillon M, Maissa C and Wong S. Symptomatic relief associated with eyelid hygiene in anterior blepharitis and MGD. Eye & Contact Lens 38(5): 306–312, 2012.

Meibomian gland dysfunction (MGD) has been re-ported in approximately 60% of dry eye sufferers. The investigators studied the effect of a particular brand of eyelid cleanser with the secondary goal of assessing a two-pronged management strategy involving a short in-tensive treatment phase, followed by a longer mainte-nance phase.

Forty subjects aged 22–74 years (54 ± 15 years) presenting with mild to moderate anterior blepharitis or MGD and eliciting an Ocular Surface Disease Index (OSDI) score of at least “mild” (13 points or less) were enrolled in the study.

The product tested was the Blephaclean (Laboratoires Théa) eyelid pad used for lid hygiene over 3 months: twice a day for 3 weeks (intensive phase) followed by once a day for the remainder (maintenance phase) of the study period.

A follow-up visit was conducted at the end of both phases. Parameters for clinical evaluation included the OSDI, Ocular Comfort and Symptoms of Dryness Ques-tionnaire, biomicroscopy of the eyelids and Snellen visual acuity.

The majority of subjects reported symptomatic relief after 3 weeks (55%) and continued to find relief during the

maintenance therapy (54%). Good compliance was dem- Images
onstrated in both the intensive and maintenance phase. Images/Getty
The OSDI demonstrated a significant decrease of 12
points after intensive therapy and 11 points at the end of Comstock/Comstock
dryness.
the study. A significant improvement in ocular comfort
was demonstrated at both time points when compared to
baseline. This same trend was also evident for ocular

Overall, this study demonstrates that lid-specific eye-lid wipes are a useful and rapid solution to ocular discomfort and dryness secondary to MGD.

Post-Script/Caveat:

  • Results were reported over a short time frame and may not be convertible to a longer study, especially with regard to patient compliance.

 

  • Short but intensive therapeutic management may improve long-term results and likely, as shown in this study, improve compliance.

 

  • Only one type of eyelid cleanser was tested; different results may occur with differing cleansers or treatment modalities.

The News: Dry eye testing

Its Implication: Providing important diagnostic information before and after treatment for dry eye.

Sullivan BD, Crews LA, Sonmez B, et al. Clinical utility of objective tests for dry eye disease: variability over time and implications for clinical trials and disease management. Cornea 31(9):1000–1008, 2012.

A total of 52 dry eye subjects (42 women and 10 men) from a general clinic population at 2 sites were enrolled in the study. The investigators sought to identify specific dry eye biomarkers, as well as their significance in monitoring therapy.

Patients were observed for 3 months with a visit nearly every 30 days. Subjects completed an OSDI survey at baseline and at each visit; additional tests included (in order) tear osmolarity, biomicroscopy, Schirmer test, tear film breakup time (TBUT), corneal staining, meibomian gland grading and conjunctival staining. The more severe eye was used for statistical analysis.

After the initial study, 10 subjects were enrolled in a 3-month therapeutic trial of topical 0.05% cyclosporine A and evaluated using the same battery of tests as in the initial study. Of the 52 eyes in the initial study, 36 were considered severe using a previously-accepted scale.

In all subjects, osmolarity measurements had the lowest variability, which was statistically different when

compared to corneal staining, conjunctival staining and meibomian gland dysfunction scoring. The low variabil-ity in osmolarity, although evident when compared to TBUT, Schirmer tests and OSDI, did not differ signifi-cantly.

A difference between severe and mild/moderate dry eye subjects was observed, with the former exhibiting a larger variation in osmolarity and OSDI scores. Osmolar-ity and OSDI differed between mild to moderate (307.1 mOsm/L, 11.5 points) and severe (324.3 mOsm/L, 45 points) dry eye subjects.

In the therapeutic arm, only osmolarity testing showed a change, with 7/10 subjects demonstrating a post-treat-ment osmolarity of 307 ± 8 mOsm/L versus a pre-treatment value of 341 ± 18 mOsm/L.

This study highlights that tear osmolarity testing is the least variable of frequently-used dry eye markers and is a highly sensitive tool to monitor dry eye treatment and management.

Post-Script/Caveat:

  • Although osmolarity tests exhibited the least variabil-ity, other clinical tests such as TBUT, Schirmer and OSDI were not statistically different and could be useful adjuncts in dry eye management.

 

  • Conventional wisdom based on early studies showed that Restasis could take 3–6 months to demonstrate symptomatic improvement. This study shows that, at least from osmolarity results, improvement may start occurring as soon as 1 month, especially in more severe cases.

 

  • In the treatment phase, clinical measurements demonstrated an earlier improvement than symptoms when compared to the OSDI.

The News: Contact lens dry eye

Its Implication: What is the effect of punctal occlusion?

Li M, Wang J, Shen M, et al. Effect of punctal occlusion on tear menisci in symptomatic contact lens wearers. Cornea 31(9):1014–1022, 2012.

Contact lens discomfort is a major reason cited for contact lens dropouts. The investigators studied changes in the symptoms, tear meniscus and several additional dry eye tests after punctal occlusion.

Forty subjects entered the study, with 20 complaining of dryness while wearing their contact lenses. The upper and lower menisci were both occluded with either .3 mm or .4 mm, 4–7 day absorbable collagen plugs.

All subjects wore an Acuvue hydrogel lens. Ultrahigh resolution optical coherence tomography (UHR-OCT) imaged both upper and lower tear menisci before punctal occlusion and at day 1, 4, 7 and 10 afterward.

Tear meniscus height, area and volume were analyzed using a customized software program. Other tests per-formed during these visits included, NIBUT (Keeler Tearscope), TBUT and Schirmer with anesthesia.

Overall, the collagen plugs caused an increase in tear menisci in both groups, but the effect lasted longer (4 days vs. 1 day) in the symptomatic group.

The authors suggest that this represents a different responsive mechanism between the 2 groups. Both groups reported improved comfort but returned to nearly baseline by day 10. A similar response was observed with NITBUT, with the symptomatic subjects improving at day 1, 4 and 7 but returning to baseline by day 10.

Post-Script/Caveat:

  • Most of the subjects in the dry eye group were women (4:1).

 

  • Only one type of contact lens was studied (hydrogel), so results may be different for differing lens materials such as silicone hydrogel.

 

  • Collagen plugs used in the current study may have varying rates of dissolution, thus one wonders if the results would be different with silicone plug placement.

 

  • This study demonstrates that the UHR-OCT is a suitable instrument to assess and monitor the tear meniscus after punctal occlusion.

The News: Ocular surface disease

Its Implication: How polyunsaturated fatty acids exert their anti-inflammatory effect.

Erdinest N, Shmueli O, Frossman Y, et al. Anti-inflammatory effects of alpha linolenic acid on human corneal epithelial cells. Invest Ophthalmol Vis Sci 53:4396–4406, 2012.

It is widely thought that inflammation plays a funda-mental role in ocular surface disease, including dry eye disease and allergic conjunctivitis.

It is believed that certain polyunsaturated fatty acids (PUFAs) can reduce ocular surface inflammation when taken orally. The study investigated the in vitro effect of PUFAs on human corneal epithelial cells.

These authors are the first to demonstrate that topical alpha-linolenic acid (ALA) has a dose-dependent anti-inflammatory effect on human corneal epithelial (HCE) cell cultures.

In vitro, HCEs were pre-treated with a variety of “inflammation inducers” (including those that mimic viral antigens), and ALA was found to reduce inflamma-tory cytokine production similar to that of dexametha-sone, a potent topical corticosteroid. Furthermore, the anti-inflammatory effect of gamma linolenic acid and linolenic acid on these same cell cultures was minimal.

Post-Script/Caveat:

  • Studies such as this may lead to exciting novel topical PUFA agents that avoid the first pass effect of the gastrointestinal tract.

 

  • These types of new therapies will avoid the side effects noted with current anti-inflammatory drugs used in ocular surface disease.

 

  • Inflammatory inducers included bacterial and viral components that may be qualitatively different than the inflammation found in ocular surface disease.

 

  • This in vitro, molecular study may not be directly indicative of what may happen in vivo.

The News: Dry eye in VA population

Its Implication: Does depression and/or PTSD influence dry eye complaints?

Galor A, Feuer W, Lee D, et al. Depression, post-traumatic stress disorder, and dry eye syndrome: a study utilizing the national United States Veterans Affairs administrative database. Amer J Ophthalmol 154:340–345, 2012.

Investigators from the Miami Veterans Administra-tion (VA) Medical Center sought to study the scope of Dry Eye Syndrome (DES) in United States veterans.

Out of almost 2.5 million patients evaluated in VA eye clinics across the nation between 2006 and 2011, almost 500,000 patients were identified as having DES.

Overall, 19% of males and 22% of females had a diagnosis of DES (i.e., ICD-9 code for DES plus dry eye therapy). Post-traumatic stress disorder (PTSD) and de-pression were linked to an increase risk for DES.

These authors claim to be the first to suggest that perhaps the psychiatric conditions themselves (and not solely the side effects of the treatment medications) are tied to the pathophysiology of DES.

Other risk factors included advancing age, female gender, sleep apnea, rosacea and non-autoimmune arthri-tis, as well as the use of antihistamines, antidepressants, anti-anxiety medications and anti-benign prostatic hyper-plasia medication.

Post-Script/Caveat:

  • Odds of DES peaked in the 6th decade of life.

 

  • The investigation demonstrated the odds of DES were nearly as high in PTSD as other commonly-associated conditions, such as arthritis and systemic autoimmune diseases.

 

  • Other factors were not assessed as causative, includ-ing environmental effects and previous surgeries.

 

  • The study was unable to clearly determine which came first, PTSD or DES.

The News: Ocular surface inflammation

Its Implication: How do contact lenses and corneal refractive therapy affect the ocular surface?

Gonzalez-Perez J, Villa-Collar C, Moreiras TS, et al. Tear film inflammatory mediators during continuous wear of contact lenses and corneal refractive therapy. Br J Ophthalmol 96:1092–1098, 2012.

Cytokines, such as Interleukin (IL)-6 and IL-8, are known inflammatory mediators in the tear film. These cytokines, combined with matrix metalloproteinase 9 (MMP-9) and epidermal growth factor (EGF) are largely responsible for the regulation of ocular inflammation and corneal wound healing.

Factors such as mechanical trauma, hypoxic stress and reduced tear turnover can result in the upregulation of these inflammatory mediators. It would therefore seem reasonable to assume that increased concentrations of these markers would be observed following extended overnight contact lens wear.

Investigators in Spain collected tear samples in non-contact lens wearers and compared them to subjects who wore silicone hydrogel lenses on a 30-day continuous-wear basis, as well as to those wearing CRT overnight orthokeratology (OK) lenses. Tear samples were collected before and after 12 months of lens wear in both test groups.

All overnight lens-wearing patients demonstrated in-creased levels of EGF; however, IL-6, IL-8 and MMP-9 were only increased in the OK group. Additionally, the concentrations of these inflammatory markers increased with the presence of corneal staining, as well as with the magnitude of myopia correction.

Post-Script/Caveat:

  • Greater levels of attempted refractive correction with orthokeratology presented a greater increase in inflammatory factors.

 

  • Adverse events were not reported or compared to increased levels of inflammatory factors in the treatment groups.

 

  • Only one type of silicone hydrogel (lotrafilcon A) and orthokeratology lens (Paragon CRT) was studied.

kjjAnterior Segment Surgery

The News: Corneal surgery

Its Implication: Do different procedures produce different levels of vision?

Post-Script/Caveat:

  • Vision, via Snellen acuity, may not be the best param-eter to assess visual performance.

 

  • The study highlights an important component of any pre-operative surgical consultation; post-operative visual performance.

¾This study represents a large, fairly well-controlled evaluation; however, the exact time frame for visual performance evaluations is not entirely clear; they appear to have been performed on the last post-opera-tive visit.

San ES, Kubaloglu A, Unal M, et al. Penetrating keratoplasty versus deep anterior lamellar keratoplasty: comparison of optical and visual quality outcomes. Br J Ophthalmol 96:1063–1067, 2012.

In a prospective randomized, interventional case se-ries, the investigators compared the optical and visual outcomes of penetrating keratoplasty (PK) versus deep anterior lamellar keratoplasty (DALK).

PK has long been touted as the gold standard in treatment of keratoconus; however, the DALK procedure has demonstrated a decreased risk of graft rejection and, with an improvement in surgical techniques, has in-creased in usage.

The subject population consisted of 99 eyes in the DALK group and 75 eyes in the PK group. All corneal surgeries were conducted by one experienced surgeon. Visual function tests included mesopic and photopic contrast sensitivity (CSV-1000E) and wavefront aberrometry (Zywave II aberrometer).

Overall, DALK proved comparable to PK in all mea-surements. Postoperative BSCVA was 20/40 or better in 82 eyes (83%) in the DALK group and in 64 eyes (85%) in the PK group (p>0.05).

Photopic contrast sensitivity was similar between the 2 surgeries; however, mesopic contrast sensitivity at 3 cycles/degree was significantly higher for DALK (p=0.01). No significant differences between groups were noted in any aberrometric parameters.

Major complications included microperforation in 8% of DALK patients, while graft rejections were observed in 9.3% of PK and 1% of DALK patients. The DALK group was able to have sutures removed sooner than the PK group (12.8 months versus 16.6 months).

lklkCorneal Disease

The News: Microbial keratitis

Its Implication: Can we determine what are the risks in contact lens wearers?

Stapleton F, Edwards K, Keay L, et al. Risk factor for moderate and severe microbial keratitis in daily wear contact lens users. Ophthalmol 119(8):1516–1521, 2012.

A 12-month, prospective national study was con-ducted in Australia from 2003–2004. The goal was to identify new cases of contact lens-related microbial kerati-tis in daily wear contact lens users.

Practitioners were enrolled to participate in the study and asked to report every 2 months. A predetermined criterion was established for eligible cases of microbial keratitis. Community controls for comparison were iden-tified using a telephone survey.

Over the course of 12 months, 125 eligible cases were reported, of which 90 were deemed moderate to severe. Corneal cultures or smears were conducted on 63 of the 90 cases, with 65% culture positive. Of these cases, 22% were gram positive bacteria, 73% gram negative bacteria (23/ 30 were pseudomonas) and 5% were acanthamoeba.

Comstock/Comstock Images/Getty Images

Risk factors in cases of moderate to severe microbial keratitis for daily contact lens users included occasional overnight use, poor storage case hygiene, smoking, solution type and infrequent storage case replacement. Con-tact lens material, age of wearer and gender were not associated with moderate to severe microbial keratitis.

The study found that patients paying proper attention to contact lens case hygiene could eliminate 50% of moderate to severe cases of microbial keratitis. Slightly more than a quarter of those incidents could also be prevented by contact lens case replacement.

Other modifiable risks included overnight wear (>1/ month but <1/week) and the type of solution used, contributing respectively to 23% and 35% of the disease load. The place of purchase for contact lenses was a significant factor for all microbial keratitis cases but was not significant when only moderate to severe keratitis cases were analyzed.

Post-Script/Caveat:

  • This study provides a list of modifiable risks that should be part of any practitioners’ set of talking points for each contact lens wearing patient.

 

  • A contact lens solution cited in the article as a risk factor will soon be unavailable on the US market.

 

  • Smoking, in addition to its overall detriment to health, increases the risk for microbial keratitis. Smoking cessation, according to this study, could decrease risk by 31%.

The News: Herpes simplex keratitis

Its Implication: Treatments based on RT-PCR results.

Hlinomazova Z, Lourkotova V, Horackova M and Sery O. The Treatment of HSV1 ocular infection using quantitative real-time pcr results. Acta Ophthalmol 90:456–460, 2012.

Real Time Polymerase Chain Reaction (RT-PCR) is a powerful tool in tagging and identifying viruses. This investigation sought to determine the usefulness of RT-PCR in diagnosing HSV-1 and in monitoring treatment effects.

The study was conducted on 212 patients with a suspected case of HSV-1 keratitis. Mean age of the group was 42 years with a range between 4 and 82 years.

Samples (3 per session) for the RT-PCR evaluation were collected at the first visit, then 1, 2, 3 and 4 weeks later. All subjects were started on topical acyclovir 5 times a day for 7–10 days.

If a uveitis was also present, the patients were started on a concurrent therapy of systemic acyclovir. When the viral load was shown to be unchanged after one week of treatment, it was determined that the patient was acyclovir resistant and subsequent treatment was changed to topical ganciclovir.

RT-PCR results showed that 85 (40%) patients were positive for HSV-1, and 16 cases were acyclovir resistant. All 16 patients were subsequently and successfully treated with ganciclovir.

Results showed that 39 patients exhibited a viral infection other than HSV-1; most commonly found vi-ruses were Adenovirus and Varicella Zoster. In addition, 120 cases were negative for HSV-1 and 7 were false negatives.

Overall, the study shows RT-PCR to be a sensitive method for detecting HSV-1 corneal infection. Further support for its effectiveness is that only 3.3% of patients testing negative responded to topical acyclovir treatment.

RT-PCR is much more sensitive and faster than tradi-tional cultivation and will result in better management and treatment of infected eyes.

Post-Script/Caveat:

  • Often HSV keratitis can masquerade as several other infectious corneal diseases, as evidenced in this study where only 60% of patients diagnosed clinically with HSV-1 on the basis of signs and symptoms were found to exhibit the actual virus.

 

  • The importance of finding a method to improve the diagnosis and monitor effectiveness of therapy would be helpful in preventing scarring and eventual vision loss in many of these patients.

 

  • Availability and cost of RT-PCR for use by many eyecare practitioners may currently be prohibitive.

The News: Keratoconus

Its Implication: Nature versus nurture

Tuft SJ, Hassan H, George S, et al. Keratoconus in 18 pairs of twins. Acta Ophthalmol 90:e482–e486, 2012.

Eighteen sets of twins were evaluated to investigate the current hypothesis that a genetic component exists in the pathogenesis of keratoconus. Keratoconus severity determination was made using the Collaborative Longitu-dinal Evaluation of Keratoconus study.

Investigators determined that 100% (13/13) of the monozygotic (identical) twins had keratoconus, and 80% (4/5) of the dizygotic (fraternal) twins had the condition.

Although all identical twins had keratoconus, they differed in age of onset and disease severity, suggesting that other components must affect the development of the condition, despite the fact that all twin pairs shared the same home environment until at least the age of 18.

Interestingly, the monozygotic twins displayed an earlier age of onset compared to dizygotic twins by approximately 4 years.

Other relatives with keratoconus were found in 16% of monozygotic twins and 60% of dizygotic twins. Other co-existent systemic and ocular diseases were uncommon, except for atopy.

Post-Script/Caveat:

  • Conclusions drawn from the study must be viewed with caution, since one of the studied groups con-tained only 5 subjects.

 

  • As indicated in this study, keratoconus is a complex disease with multiple genes determining its emer-gence, with a suggestion that environmental factors play a role in its severity.

hhhContact Lenses

The News: : Multifocal contact lenses

Its Implication: Defining “ghosting” experienced by presbyopic contact lens wearers.

Kollbaum PS, Dietmeier BM, Jansen M, et al. Quantification of ghosting produced with presbyopic contact lens correction. Eye & Contact Lens 38:252–259, 2012.

It is often challenging to manage patients who see 20/ 20 or better on the Snellen acuity chart, but report poor vision while wearing a presbyopic contact lens correction. A commonly-heard vision complaint is one of image “ghosting.”

Investigators from Indiana University School of Op-tometry sought to develop and validate a questionnaire to quantify a patient’s perceived image quality, specifically as it relates to this ghosting phenomenon.

To validate their questionnaire, pre-presbyopic sub-jects wearing their best distance spectacle lens correction were tested to see if they could accurately detect and quantify four ghosting dimensions (i.e., direction, posi-tion offset, focus/blur and intensity).

Individual letters with varying amounts of these ghost-ing dimensions were computer-generated and shown on a printed sheet and an LED monitor. Once it was determined that subjects could in fact identify these distinct features of ghosting with very high accuracy, the questionnaire was applied in a clinical setting.

Fifty-four presbyopic subjects viewed a focused tar-get monocularly, with a spherical, center-near design multifocal soft contact lens in their appropriate distance and add powers. They scored observed ghosting in the same manner previously tested.

Subjects were also asked to give an “overall ghosting” rating on a scale of 0–100. Thirty-three percent (4/12) and 34 percent (8/23) of subjects reported ghosting with low and medium adds respectively, while 79 percent (15/19) reported ghosting with high adds.

The dimension that correlated with a higher overall ghosting rating related to the focus/blur of the ghost image itself (i.e., the more in-focus the ghost image was, the higher the overall ghosting rating).

Although the authors readily admit the current ques-tionnaire requires refinement, they believe this method can easily be implemented in the clinic to produce accu-rate patient assessments of perceived ghosting with any multifocal lens design.

Bausch + Lomb is pleased to support the development and distribution of the Contact Lens & Anterior Segment Update under the editorship of Dr. William Miller. CLASU has been a long standing educational tool that benefited educators and students alike. Providing a summary of timely basic and clinical research that has been through the peer-reviewed process will bring greater attention to ocular surface health topics in a useful format. Bausch + Lomb has generously provided an unrestricted educational grant to support this publication.

Post-Script/Caveat:

  • Validation of questionnaire effectiveness was con-ducted on pre-presbyopic subjects who, interestingly, overestimated low levels of blur and underestimated more severe levels with regard to direction, focus and intensity.

 

  • Effects of binocular multifocal contact lens wear or other lens designs (center distance) were not tested.

 

  • This study confirms that as the add power in a multifocal soft contact lens is maximized, the poten-tial for greater visual disturbance increases.

 

  • A validated pre-assessment criterion would be a welcome addition to clinical practice to aid in determining successful multifocal patients.