Intraocular pressure screening during high-volume cataract surgery outreach in Ethiopia

Introduction

Glaucoma is the leading cause of irreversible blindness worldwide and is often undetected in resource-limited settings. Early screening and treatment of elevated intraocular pressure (IOP) reduces both the development and progression of visual field defects. IOP screening in developing countries is limited by access to ophthalmic equipment, trained ophthalmic staff, and follow up. High-volume cataract surgery outreaches in resource-limited countries provide ample opportunity for glaucoma screening, intervention and follow up.

Methods

This prospective cross-sectional study took place during a cataract outreach campaign sponsored by the Himalayan Cataract Project (HCP) in partnership with Felege Hiwot Hospital in Bahir Dar, Ethiopia, during April 5th – April 10th 2021. IOP was measured on the surgical eye of patients before undergoing small incision cataract surgery (SICS) using rebound tonometry with an iCare tonometer model IC100.

Results

Intraocular pressure (IOP) was measured in 604 eyes of 595 patients who received SICS. Mean IOP was 12.1 mmHg (SD = 5.0 mmHg). A total of 29 patients had an IOP greater than 21 mmHg representing 4.8% of total IOP measurements. A total of 17 patients received oral acetazolamide prior to surgery to acutely lower IOP. Six of these patients had their surgery delayed due to elevated IOP and 9 patients received excisional goniotomy at the time of SICS. A temporal approach during SCIS was taken for all patients with elevated IOP to allow for possible trabeculectomy at a future date.

Discussion

IOP screening during high-volume cataract outreach campaigns can be performed safely, accurately and on a large scale with minimal resources and supplemental training. Pre-operative IOP measurement can improve surgical care at the time of cataract surgery as well as help establish long-term follow up for patients with glaucoma.

Characterising transnational ophthalmic surgical partnerships by engagement and training

BACKGROUND

Transnational ophthalmic partnerships exist between high-income countries (HICs) and low- and middle-income countries (LMICs) in varying capacities. We analyzed partnership stakeholders to better understand and address disparities in ophthalmic surgical care.

METHODS

An international Web search was conducted to identify surgeons, foundations or organisations participating in ophthalmic delivery and/or capacity building from 2010 to 2019. Partnerships were defined through clinical activities, education and training and/or research support. Descriptive data on current ophthalmic partnerships were collected from published reports, literature reviews and information on stakeholder webpages. Partnerships were classified by the extent of engagement and training: grade I 'engagement' represented documented partnerships of at least 1 year and grade I 'training' limited or poorly defined skills transfer programmes, while grade III 'engagement' represented partnerships with well-documented fiscal investment and/or research productivity and grade III 'training' established training programmes. Data were analysed using descriptive statistics and geospatially depicted on Tableau (Mountain View, CA) and ArcMap software (Redlands, CA).

RESULTS

In total, 209 unique HIC-LMIC partnerships encompassing 92 unique countries were described. The most common HIC partners were from North America (123; 59%), followed by Europe (75; 36%). The most common LMIC partners were from Africa (102; 49%), followed by Asia-Pacific (54; 26%) and Latin America (44; 21%). Additionally, partnerships most frequently provided services in cataract (48%), glaucoma (25%) and diabetic retinopathy (25%). The most common 'engagement' classifications were grade I (36%) or II (40%); the most common 'training' classifications were grade I (61%) or II (23%).

CONCLUSION

Transnational ophthalmic partnerships exist with varying degrees of both engagement and training. Partnerships are stronger in research collaboration and direct services, and weaker in LMIC-directed training programmes.

Artificial intelligence in global ophthalmology: using machine learning to improve cataract surgery outcomes at Ethiopian outreaches

Differences between target and implanted intraocular lens (IOL) power in Ethiopian cataract outreach campaigns were evaluated, and machine learning (ML) was applied to optimize the IOL inventory and minimize avoidable refractive error. Patients from Ethiopian cataract campaigns with available target and implanted IOL records were identified, and the diopter difference between the two was measured. Gradient descent (an ML algorithm) was used to generate an optimal IOL inventory, and we measured the models performance across varying surplus levels. Only 45.6% of patients received their target IOL power and 23.6% received underpowered IOLs with current inventory (50% surplus). The ML-generated IOL inventory ensured that more than 99.5% of patients received their target IOL when using only 39% IOL surplus. In Ethiopian cataract campaigns, most patients have avoidable postoperative refractive error secondary to suboptimal IOL inventory. Optimizing the IOL inventory using this ML model might eliminate refractive error from insufficient inventory and reduce costs.

Prevalence and Severity of Diabetic Retinopathy among Diabetic Patients Presenting to a Tertiary Eye Hospital in Nepal

PURPOSE:

The purpose of the study is to evaluate the prevalence and severity of diabetic retinopathy (DR) among all diabetic patients presenting to a tertiary eye care center in Nepal over a 3-year period.

MATERIALS AND METHODS:

This was a retrospective review of all clinical records from the initial presentations of diabetic patients at the Tilganga Institute of Ophthalmology (TIO) from 2012 to 2014.

RESULTS:

In total, 8855 patients were identified who presented to TIO with a prior diagnosis of diabetic mellitus (DM) during the study period. DR was found in 1714 patients (19.4%) at the time of initial presentation, 1305 (14.7%) of which had nonproliferative DR (PDR), while 617 (6.9%) demonstrated diabetic macular edema (DME) and 409 (4.6%) demonstrated PDR. Of the 1714 patients with DR, 825 (48.1%) required treatment at initial presentation for DME and/or PDR. Male gender, hypertension, age at presentation, and interval from diagnosis of DM to initial eye consultation were significantly associated with the presence of DR (P < 0.05).

CONCLUSIONS:

The prevalence of DR among patients with DM was 19.4%, which is lower than previously published estimates. However, among patients diagnosed with DR, over half presented with a vision-threatening complication warranting some measure of initial treatment.

Comparison of early versus standard timing for silicone stent removal following External Dacrocystorhinostomy under local anaesthesia

INTRODUCTION

The first line treatment for nasolacrimal duct obstruction (NLDO) is external dacrocystorhinostomy (DCR). Following DCR, patients are required to return to Tilganga Institute of Ophthalmology (TIO) six weeks postoperatively for the removal of a silicone stent. As the majority of patients travel large distances at significant cost to reach TIO, most often patients remain within Kathmandu during this six weeks interval. This places a large financial burden on patients.

METHODS

A randomized controlled trial was designed to compare patient outcomes after early (two weeks postoperatively) versus standard (six weeks postoperatively) removal of silicone stents. 50 selected patients were randomized into two equal groups.

RESULTS

At the time of publication, 31 patients (14 in group A and 17 in group B) had completed three months follow up. A success rate of 92.9% was noted in Group A and a success rate of 94.1% observed in group B. No significant difference was found between the two groups for success rate and rate of complications.

CONCLUSION

Early tube removal post DCR appears to cause no significant difference in outcome or complication rates compared to standard tube removal.

Comparison of early versus standard timing for silicone stent removal following External Dacrocystorhinostomy under local anaesthesia

INTRODUCTION

The first line treatment for nasolacrimal duct obstruction (NLDO) is external dacrocystorhinostomy (DCR). Following DCR, patients are required to return to Tilganga Institute of Ophthalmology (TIO) six weeks postoperatively for the removal of a silicone stent. As the majority of patients travel large distances at significant cost to reach TIO, most often patients remain within Kathmandu during this six weeks interval. This places a large financial burden on patients.

METHODS

A randomized controlled trial was designed to compare patient outcomes after early (two weeks postoperatively) versus standard (six weeks postoperatively) removal of silicone stents. 50 selected patients were randomized into two equal groups.

RESULTS

At the time of publication, 31 patients (14 in group A and 17 in group B) had completed three months follow up. A success rate of 92.9% was noted in Group A and a success rate of 94.1% observed in group B. No significant difference was found between the two groups for success rate and rate of complications.

CONCLUSION

Early tube removal post DCR appears to cause no significant difference in outcome or complication rates compared to standard tube removal.

Blindness, cataract surgery and mortality in Ethiopia

PURPOSE

To examine the relationships between blindness, the intervention of cataract surgery and all-cause mortality in a rural Ethiopian population.

DESIGN

Population-based, interventional prospective study.

METHODS

Community-based detection methods identified blind Ethiopian persons from two selected kebeles in Amhara region, Ethiopia. Data from 1201 blind patients were collected-628 cataract-blind and 573 blind from other conditions. Free cataract surgery was provided for consenting, cataract-blind patients. Follow-up surveys were conducted after 12 months (±1 month)-the main outcome measure for this report is all-cause mortality at 1 year.

RESULTS

During the follow-up period, 110 persons died from the selected population (mortality 9.2%), which consisted of those cataract-blind patients who received cataract surgery (N=461), cataract-blind patients who did not receive surgery (N=167) and all non-cataract-blind patients (N=573). Of the 461 patients who received cataract surgery, 44 patients died (9.5%). Of the 740 patients who did not receive surgery, 66 died (8.9%)-28 patients from the cohort of cataract-blind patients who did not receive surgery (16.8%) and 38 patients from the cohort of non-cataract blind (6.6%). Subgroup analysis revealed significantly increased odds of mortality for cataract-blind patients over 75 years of age who did not receive surgery and for unmarried patients of all age groups.

CONCLUSIONS

In this population, mortality risk was significantly elevated for older cataract-blind patients when compared with non-cataract-blind patients-an elevation of risk that was not noted in an age-matched cohort of cataract-blind patients who underwent cataract surgery as early as 1-year follow-up.

Scleral fixation of a posterior chamber intraocular lens combined with penetrating keratoplasty in an aphakic patient with microcornea and microphthalmia

A 66-year-old man with microcornea and microphthalmia required a corneal transplant for bullous keratopathy. The patient suffered from congenital cataracts and was left aphakic at the time of the original surgery because of the special challenge of operating on his eye. To improve his vision, we elected to place an intraocular lens (IOL) into his eye as an 'open sky' procedure during corneal transplant. However, the implantation was difficult because of the small size of this eye. The surgeon used a novel approach to fixing the IOL to the sclera in which he penetrated the IOL and sutured the IOL through this hole. Following the procedure, the patient reported improvement in his vision and great satisfaction. This case report describes a manoeuvre of fixating an IOL to the sclera by piercing the IOL optic.

The use of glycerol-preserved corneas in the developing world

Corneal opacity is the third leading cause of blindness in the developing world and encompasses a wide variety of infectious, inflammatory and degenerative eye diseases. Most caes of corneal blindness are treatable with partial or full-thickness keratoplasty, provided adequate corneal tissue and surgical skill is available. However, access to sightrestoring keratoplasty in developing countries is limited by the lack of developed eye banking networks and a critical shortage of tissue suitable for transplantation. Beyond the developed world, corneal transplantation using fresh corneal tissue (FCT) is further hindered by unreliable storage and transportation facilities, unorganized distribution networks, the cost-prohibitive nature of imported tissue, unreliable compliance with medications and follow-up instructions and inadequate health and education services. Glycerol-preserved corneas overcome many of these limitations inherent to the use of FCT. As surgical innovation in lamellar corneal surgery expands the potential use of acellular corneal tissue, long-term preservation techniques are being revisited as a way to increase availability of corneal tissue to corneal surgeons throughout the developing world. Herein, we discuss the advantages of using and the applications for glycerol-preserved corneal tissue throughout the developing world.

Etiologic diagnosis of corneal ulceration at a tertiary eye center in Kathmandu, Nepal

PURPOSE

To determine the etiologic diagnosis of infectious corneal ulcers at Tilganga Institute of Ophthalmology, a tertiary teaching hospital in Kathmandu Nepal, from 2006-2009.

METHODS

This study involved a review of all microbiology records at Tilganga Institute of Ophthalmology from August 2006 through July 2009. Microbiologic records from the corneal scrapings of all patients suspected of having infectious corneal ulcers were included.

RESULTS

Corneal scrapings were obtained from 468 patients. The average patient age was 52 years, and 55% of the affected cases were males. Microorganisms were grown from 185 of the corneal scrapings (40%). Pure bacterial cultures were obtained from 72 patients (39%), and pure fungal cultures were obtained from 113 patients (61%). Gram stain was 75% sensitive (95% confidence interval, 0.632-0.841) in identifying bacterial infection, whereas KOH prep was 80.5% sensitive (95% confidence interval, 0.718-0.871) in identifying fungal organisms. Of 72 bacterial isolates, 50 isolates (69%) were Streptococcus pneumoniae, the most common organism isolated in this study. Of 113 fungal isolates, 40 of isolates (35%) were identified as Aspergillus sp.

CONCLUSIONS

Fungal organisms (61%) are the most common cause of infectious keratitis in this patient population. Of all organisms, S. pneumoniae was the most common organism identified. Smear microscopy is reliable in rapidly determining the etiology of the corneal infection and can be used to help guide initial therapy in this setting.

No Pathogenic Mutations Identified in theCOL8A2Gene or Four Positional Candidate Genes in Patients with Posterior Polymorphous Corneal Dystrophy

PURPOSE

To identify the genetic basis of posterior polymorphous corneal dystrophy (PPCD) through screening of four positional candidate genes and the COL8A2 gene, in which a presumed pathogenic mutation has previously been identified in affected patients.

METHODS

DNA extraction, PCR amplification, and direct sequencing of the COL8A2, BFSP1, CST3, MMP9, and SLPI genes were performed in 14 unrelated, affected patients and in unaffected family members.

RESULTS

In the COL8A2 gene, the previously identified, presumed pathogenic mutation (Gln455Lys) was not discovered in any of the affected patients. A missense mutation, Thr502Met, was identified in 2 of the 14 affected probands, although it was not considered to be pathogenic, as it has been identified in unaffected individuals. Although several novel and previously identified single nucleotide polymorphisms producing synonymous and missense amino acid substitutions were identified in the COL8A2, BFSP1, CST3, MMP9, and SLPI genes, no presumed pathogenic sequence variants were found.

CONCLUSIONS

No pathogenic mutations were identified in the COL8A2 gene or in several positional candidate genes in a series of patients with PPCD, indicating that other genetic factors are involved in the development of this autosomal dominant corneal dystrophy.

Penetrating Keratoplasty in Nepal

PURPOSE

To identify indications and outcomes in a large series of penetrating keratoplasty surgeries performed in Nepal.

METHODS

A retrospective case series of 472 consecutive penetrating keratoplasty surgeries (408 patients) performed at Tilganga Eye Center, Kathmandu, Nepal from June 1994 to September 1999.

RESULTS

Mean recipient age was 39.2 years (+/- 19.7 years). Main indications for PKP were corneal scar (37%), adherent leukoma (35%), perforation or impending perforation (9%), pseudophakic bullous keratopathy (6%), keratoconus (4%), and aphakic bullous keratopathy (3%). Mean duration of follow-up was 27.6 +/- 25.1 months. Sixty-five percent of available grafts were clear at 6 months, and 70% of available grafts were clear at 3 years. Six months postoperatively, 15% of patients had acuity better than 6/18, 37% had acuity between 6/18 and 6/60, and 17.7% had acuity between 6/60 and 3/60. Common causes of graft failure were endothelial failure (43%), increased intraocular pressure (15%), ulcer (14%), and trauma (7%).

CONCLUSIONS

The corneal diseases and indications for transplant surgery in Nepal are different from those in the Western world. Despite these differences, penetrating keratoplasty is a successful and reasonable way to reduce corneal blindness in developing nations.

Large-diameter lamellar keratoplasty in severe ocular alkali burns: A technique of stem cell transplantation

PURPOSE

To evaluate the efficacy of large-diameter lamellar keratoplasty in cases of severe ocular alkali burns.

DESIGN

Prospective, noncomparative, interventional case series.

PARTICIPANTS

Nine eyes of nine patients with severe ocular alkali burns (grade III/IV) exhibiting corneal vascularization, conjunctivalization, and chronic inflammation were recruited from the Cornea Clinic of Dr. Rajendra Prasad Centre for Ophthalmic Sciences, New Delhi, a tertiary eye care center.

INTERVENTION

Large-diameter lamellar keratoplasty was performed using McCarey-Kaufman media-preserved donor corneas. The patients were followed up for a minimum of 6 months.

MAIN OUTCOME MEASURES

Symptomatic relief, time to epithelialization, best-corrected visual acuity, Schirmer I, tear film break-up time, and central corneal clarity were the parameters evaluated.

RESULTS

The mean duration between the injury and surgery was 29.5 +/- 19.4 months. No intraoperative complications were seen. Successful epithelialization of the ocular surface was achieved in all but one eye, and the mean time to epithelialization was 5.2 +/- 4.9 days. One eye had a persistent epithelial defect which was managed with a bandage soft contact lens. All patients achieved symptomatic relief. The preoperative best-corrected visual acuity was </=1/60 in all the patients. There was a significant improvement in vision in six eyes postoperatively (P = 0.013). The corneal clarity was grade 2+ or better in five eyes and 1+ in four eyes. No recurrence of corneal vascularization or signs of rejection were seen in any eye during the mean follow-up of 7.4 +/- 3.2 months. Causes of no improvement of vision included the presence of subepithelial nebulomacular haze in one eye caused by persistent epithelial defect and residual stromal haze.

CONCLUSIONS

Large-diameter lamellar keratoplasty is a useful therapeutic modality in cases of severe alkali burns. It is a single-stage procedure that provides a stable ocular surface because of stem cell supplementation and may visually rehabilitate the patient.

Low-cost high-volume extracapsular cataract extraction with posterior chamber intraocular lens implantation in Nepal

OBJECTIVE

To improve current clinical practices and ways of thinking about the problem of curable Third-World blindness resulting from cataract.

DESIGN

A two-site prospective, nonrandomized, comparative clinical trial.

PARTICIPANTS

Patients from 2 distinct surgical venues underwent cataract surgery following the same carefully outlined protocol: 62 consecutive cases from the Tilganga Eye Centre in Katmandu, Nepal, and 207 cases from a remote eye camp in rural Chaughada, Nepal.

INTERVENTION

Extracapsular cataract extraction with posterior chamber intraocular lens (IOL) implantation surgery using a technique developed by Dr. Sanduk Ruit of the Tilganga Eye Centre in conjunction with the Medical Directorate of the Fred Hollows Foundation of Australia. Also presented is the teaching method used to help make local doctors proficient in this technique.

MAIN OUTCOME MEASURES

Visual acuity recorded at 2 months after surgery as well as surgical complications.

RESULTS

Preoperative visual acuities for the 62 patients from the Tilganga Eye Centre ranged from 20/60 to light perception only (4 patients were untested). At 2 months after surgery, 87.1% had a best-corrected visual acuity of 20/60 or better. There were zero major surgical complications reported from the Tilganga group. Of the 207 patients at the Chaughada eye camp, preoperative visual acuities (recorded for 177 [85.5%]) ranged from 20/200 or greater to light perception only. One hundred eighty-nine (91.3%) of the patients returned for an examination at 2 months after surgery, at which time 54.5% had an uncorrected visual acuity of 20/60 or greater, improving to 74.1% with correction. There were six (2.9%) surgical complications documented at Chaughada.

CONCLUSIONS

Because the average operative time using the technique presented here is less than 10 minutes per case and the cost per surgery is less than $20, the surgical results are significant in addressing the massive problem of cataract blindness in the Third World. With some changes in preoperative care, a simplified surgical technique, the development of local lens factories, and the implementation of teaching programs, effective lens implantation cataract surgery can be done in high volume at affordable costs in remote areas of underserved nations.

High-altitude retinopathy and altitude illness

OBJECTIVE

To determine the relationship between high-altitude retinopathy (HAR) and other altitude-related illnesses and establish a classification system for HAR.

DESIGN

Observational case series.

PARTICIPANTS

All 40 climbers among 3 Himalayan expeditions who ascended to altitudes between 16,000 and 29,028 feet above sea level (summit of Mt. Everest) were examined for signs of HAR and altitude illness (AI).

METHODS

All subjects had dilated fundus examinations before the ascent, intermittent fundus, and medical examinations during the climb and a dilated fundus and medical examination within 2 days after attaining their highest altitude.

MAIN OUTCOME MEASURES

Careful fundus drawings or fundus photography or both were obtained for all participants. All subjects gave a subjective assessment of their symptoms of acute mountain sickness (AMS) and were assessed clinically for signs of high-altitude cerebral edema (HACE).

RESULTS

Nineteen of 21 climbers who ascended above 25,000 feet developed HAR. Fourteen of 19 climbers who attained altitudes between 16,000 and 25,000 feet were found to have retinopathy. A grading system for HAR describing the severity of the retinopathy was developed. Correlation of the retinopathy with other AI showed that AMS was endemic and that a statistically significant correlation exists between HAR and HACE (P = 0.0240).

CONCLUSION

Recognizing advancing grades of HAR may allow physicians to recommend initiating empiric treatment with oxygen, steroids, diuretics and immediate descent to prevent HAR progression, macular involvement, or potentially fatal HACE. High-altitude retinopathy is both a significant component of and a predictor of progressive AI.

Cluster of diplopia cases after periocular anesthesia without hyaluronidase

PURPOSE

To describe a cluster of cases of iatrogenic diplopia after cataract surgery that occurred in 1998, when hyaluronidase was unavailable for use in periocular anesthetic regimens.

SETTING

The clinical practices of the authors.

METHODS

This study comprised a retrospective chart review.

RESULTS

Twenty-five cases of transient or permanent diplopia were reported. Of these, 13 eyes had retrobulbar and 10 had peribulbar injections; in 2 cases the injection technique was unknown. The inferior rectus was affected in 19 eyes; of these, 1 had a temporary palsy and 18 had permanent restriction. Temporary paresis developed in the lateral rectus in 5 cases and the superior rectus in 2. Eleven cases were submitted by 4 anterior segment surgeons, who collectively had a zero incidence of iatrogenic postoperative diplopia in the preceding 4 to 11 years of practice (approximately 6900 cases).

CONCLUSION

Hyaluronidase may be more important than previously suspected in preventing anesthetic-related damage to the extraocular muscles. The inferior rectus muscle is particularly vulnerable, presumably because of the injection technique.

Oversized grafts in children

OBJECTIVE

To evaluate the efficacy of oversized corneal grafts in the pediatric age group.

DESIGN

Prospective, nonrandomized clinical trial.

PARTICIPANTS AND INTERVENTION

Forty pediatric patients with unilateral or bilateral corneal opacification of congenital or acquired origin underwent corneal grafting surgery over a period of 2 years using donor corneal buttons oversized by 1 mm.

MAIN OUTCOME MEASURES

The parameters evaluated were indications for keratoplasty, graft clarity, visual acuity, keratometry, spherical equivalent, anterior chamber depth, and complications.

RESULTS

Corneal ulceration was the most common cause of corneal opacification (25%), followed by trauma (20%) and sclerocornea (20%). At 1 year, clear grafts were achieved in 85% of the cohort. The average keratometry at the end of 1 year was 43.28 +/- 1.65 diopters (D) in the congenital opacity group and 43.04 +/- 2.20 D in the acquired group. The keratometric astigmatism was 3.60 +/- 2.60 D in the congenital group and 2.52 +/- 2.20 D in the acquired group. Oversized grafts provided an adequate anterior chamber depth of 2.20 +/- 0.612 mm in the congenital group and 2.36 +/- 0.302 mm in the acquired group. Visual acuity of 20/80 or better was recorded in only 30% of cases in the congenital group as opposed to 47% with acquired opacities. Nine cases had episodes of graft rejection.

CONCLUSION

Oversizing donor buttons by 1 mm provides adequate anterior chamber depth and increases the morphologic success of corneal grafting in children.

Corneal superinfection in acute hemorrhagic conjunctivitis

PURPOSE

This study aimed to evaluate the clinical profile, microbial spectrum, management modalities, and visual outcome in cases of corneal superinfection that occurred after an epidemic of acute hemorrhagic conjunctivitis.

METHOD

A retrospective analysis of 14 eyes of 13 patients who were referred to a tertiary eye-care center with corneal ulceration after an episode of acute hemorrhagic conjunctivitis was undertaken. The parameters analyzed were age, sex, prior use of topical medications, predisposing factors, ulcer characteristics, organisms isolated, success of medical therapy and surgery, and visual outcome.

RESULTS

A definite history of topical corticosteroid use to treat acute hemorrhagic conjunctivitis was elicited in 12 (86%) eyes. Cultures were positive in 86% (12/14) eyes. Organisms isolated were Pseudomonas aeruginosa (three eyes, 25%), Fusarium species (three eyes, 25%), Aspergillus species (two eyes, 16%), and Staphylococcus aureus (two eyes, 16%). Mixed infection occurred in two patients. After discontinuation of topical corticosteroids, all patients received antimicrobial therapy. The keratitis resolved in seven eyes. Therapeutic penetrating keratoplasty was required in five eyes. Two patients were lost to follow-up.

CONCLUSIONS

Corneal superinfection may occur after acute hemorrhagic conjunctivitis. Use of topical corticosteroids to treat acute hemorrhagic conjunctivitis may predispose an already compromised cornea to develop microbial keratitis and such a practice should be discouraged.

Comparison of the effects of enucleation and orbital reconstruction using free-fat grafts, dermis grafts, and porous polyethylene implants in infant rabbits

Twenty-nine infant rabbits from four litters were randomly assigned to three groups. No surgery was performed on left eyes. All right eyes were enucleated. Group 1, the control group, had no right-socket reconstruction. Group 2 had reconstruction using free-fat and dermis grafts. Group 3 had reconstruction using porous polyethylene implants. On attaining adult size, rabbits were killed, decapitated, and prepared for measurements. Orbital volume measurements were performed twice and orbital entrance areas were determined once. No significant differences were noted between first and second measurements of orbital volumes. Right orbital volumes were significantly smaller than left orbits in all groups except for the second measurement of the polyethylene implant group. Right orbital entrance areas were significantly smaller than left areas in the control and the free-fat and dermis graft groups. Right orbital entrance areas of the polyethylene group were not significantly smaller than the corresponding left orbital entrance areas. The use of free-fat and dermis grafts for orbital reconstruction in anophthalmic infant rabbits did not significantly stimulate orbital bone growth. In one trial, the polyethylene implant group displayed right orbital volumes and orbital entrance areas that were not significantly smaller than controls.

Refractive versus Corneal Changes After Photorefracive Keratectomy for Astigmatism

PURPOSE

To define measures of assessing success and subsequent ways to improve excimer laser treatment of astigmatism.

METHODS

We studied 97 eyes of 79 patients, followed for 12 months, that underwent photorefractive keratectomy (PRK) for myopia and astigmatism with a VISX 20/20 excimer laser. Preoperative spherical equivalent refraction at the corneal plane was between -1.00 and -15.00 D. Mean preoperative refractive astigmatism at the spectacle plan was -2.17 +/- 1.05 D (range, -1.25 to -6.00 D), which is -1.81 +/- 0.86 D (range -1.04 to -4.97 D) when calculated at the corneal plane. All patients were examined before and after surgery; examination included refraction, keratometry, and topography measurement.

RESULTS

The success in treatment of astigmatism appeared measurably less than the treatment of sphere when analogous indices were used for assessment. Success in astigmatism surgery improved, as measured by all parameters, after an additional 20% was applied to astigmatism treatment magnitude indicated by the VISX computer algorithm. The sequential modes of treatment undercorrected astigmatism magnitude to a greater extent than elliptical, but equivalent success rates were present in view of the greater astigmatic changes attempted using the sequential mode. The elliptical mode tended to produce a greater undercorrection of associated sphere (p = 0.313). Results measured by refraction showed a larger change than those measured by topography and keratometry.

CONCLUSION

During PRK with the VISX 20/20 laser, adjustment for undercorrection of astigmatism treatment achieves a fuller correction of astigmatism. When measuring astigmatic changes, results are different when comparing refractive astigmatism changes with corneal astigmatism changes measured by keratometry and topography.

Astigmatic change 1 year after excimer laser treatment of myopia and myopic astigmatism. Melbourne Excimer Laser Group

PURPOSE

To evaluate the surgically induced astigmatism (SIA) 1 year after excimer laser photorefractive astigmatic keratectomy (PARK) and photorefractive keratectomy (PRK).

SETTING

Royal Victorian Ear and Eye Hospital, Melbourne, Australia.

METHODS

This study comprised 333 PARK patients and 155 PRK patients treated with a VISX 20/20 excimer laser and followed prospectively for 12 months. Vector analysis of the change in astigmatism was used to calculate the SIA in the PRK group and the percentage of astigmatism corrected in the PARK group.

RESULTS

Among patients with low cylinders astigmatic correction varied greatly, particularly in those treated for large amounts of myopia. The spherical PRK treatments yielded a mean induced postoperative astigmatism of 0.47 diopter. There was a linear relationship between this inadvertent SIA and increasing myopia.

CONCLUSION

Excimer laser surgery for myopia creates a low degree of random, unpredictable SIA that may be the result of irregular epithelial thickening during postoperative healing. This creates a background noise of astigmatic change upon which the targeted astigmatic correction is superimposed.

Predictive leg strength values in immediately prepubescent and postpubescent athletes

Sixty healthy, athletic children were treated on a Cybex II Dynamometer to obtain values for the relative strengths of the major muscle groups of the lower extremity. Prepubescent and postpubescent boys and girls were tested. Of the anthropometric parameters measured, lean body weight correlated best with maximal torque force development. In prepubescent children, the mean maximal quadriceps torque force, measured in foot-pounds at 60 deg/sec, is equal to 70% of the lean body weight. In postpubescent subjects, the mean peak quadriceps torque equalled 80% of the lean body weight in girls and 90% of the lean body weight in boys. Correlations can be established between the maximal torque force generated by the quadriceps and the strength of the hamstrings, ankle dorsiflexors, and plantar flexors. The values obtained are useful in planning training and rehabilitation programs and in determining when an injured young athlete can safely return to his or her sport.