Factors associated with variability in retinal nerve fiber layer thickness measurements obtained by optical coherence tomography

OBJECTIVE

To identify factors associated with variability in retinal nerve fiber layer (RNFL) thickness measurements obtained by optical coherence tomography (OCT).

DESIGN

Retrospective observational case series.

PARTICIPANTS

One hundred fifty consecutive patients with known or suspected glaucomatous optic nerve damage undergoing OCT imaging for RNFL thickness measurement.

METHODS

One eye with known or suspected glaucoma from each patient was scanned twice within the same visit using the Stratus OCT's fast nerve fiber layer thickness acquisition protocol. For each scan, the average RNFL thickness, signal strength (a measure of the amount of light reflecting back from the retina), and analysis confidence (AC, a measure of the quality of the data as reported by the OCT software) were recorded. Retinal nerve fiber layer thickness measurements of the initial and repeat scans for each case were compared, and the difference in thickness measurements was correlated with difference in signal strength, AC (either low or normal), and the average RNFL thickness.

MAIN OUTCOME MEASURE

Difference in RNFL thickness.

RESULTS

The mean difference in RNFL thickness between the initial and repeat scans was 10 microns (12.5%; range, 0.04-86.15 microns). Difference in signal strength between initial and repeat scans positively correlated with the difference in RNFL thickness (Spearman correlation coefficient = 0.44; P<0.001), whereas the average nerve fiber layer thickness negatively correlated with the difference in RNFL thickness (Spearman correlation coefficient = -0.25; P = 0.002). The presence of a scan with low AC was associated with a lower average RNFL thickness and a greater difference in RNFL thickness between the initial and repeat scans.

CONCLUSIONS

Signal strength variability, low AC, and low RNFL thickness are associated with variability in RNFL thickness measurements obtained by Stratus OCT. Comparability of RNFL thickness measurements between visits may be improved if scans of similar signal strengths without low AC are obtained. This is especially important for patients with moderate glaucomatous optic nerve damage and for patients from whom good quality scans are not obtainable.

Intravitreal triamcinolone acetonide for the treatment of immune recovery uveitis macular edema

PURPOSE

To evaluate the use of intravitreal triamcinolone (IVTA) for the treatment of macular edema secondary to immune recovery uveitis (IRU) in patients with AIDS.

DESIGN

Prospective, consecutive, interventional case series.

PARTICIPANTS

Eight eyes of 7 patients receiving 13 injections.

METHODS

Prospective, consecutive, interventional case series of 13 injections involving 8 eyes in 7 patients who underwent an intravitreal injection of 20 mg decanted triamcinolone acetate for fluorescein angiographically proven IRU-related macular edema.

MAIN OUTCOME MEASURES

The primary outcome measure was vision (using the Early Treatment Diabetic Retinopathy Study chart). Other outcome measures included fluorescein angiography and optical coherence tomography.

RESULTS

Visual acuity improved at all time points and was statistically significant at the 1-month and 3-month follow-up examinations. The average visual improvement was 3 lines at 3 months. Retinal volume and thickness improvement were statistically significant at all time points. All patients had a minimum follow-up of 9 months, and there were no cases of cytomegalovirus reactivation.

CONCLUSIONS

Previous studies showed that treatment with sub-Tenon repository steroids for the treatment of macular edema of IRU was only marginally effective. However, the current study shows that IVTA can be an effective short-term treatment for macular edema secondary to IRU in patients with AIDS. Longer follow-up is needed to assess the durability of the effect and to monitor for longer-term complications and outcomes.

Esterified estrogens combined with methyltestosterone raise intraocular pressure in postmenopausal women

PURPOSE

To investigate the effect of esterified estrogens combined with methyltestosterone (EECM) (Estratest, Solvay, Pharmaceuticals, Inc, Baudette, Minnesota, USA) on intraocular pressure (IOP) in postmenopausal women.

DESIGN

Observational case series.

METHODS

The IOP of 13 consecutive postmenopausal women with dry eye syndrome were recorded before and during EECM therapy (1.25 mg of esterified estrogens and 2.5 mg of methyltestosterone for several months).

RESULTS

The mean IOP increased from a baseline of 15.0 mm Hg before treatment to 18.2 mm Hg on EECM therapy (P < .0001) after a median duration of 11.3 months (range, 0.9 to 24 months). The increase in IOP was statistically significant at the 0.05 level of significance within three months and continued over 12 months. Two patients whose pressures increased (>4 mm Hg) returned to baseline levels after EECM was discontinued.

CONCLUSIONS

Esterified estrogens combined with methyltestosterone produce a clinically significant increase in IOP in postmenopausal women with dry eye syndrome.

Errors in retinal thickness measurements obtained by optical coherence tomography

OBJECTIVE

To report the frequency and severity of optical coherence tomography (OCT) retinal thickness measurement errors and to describe parameters that predict these errors.

DESIGN

Observational case series.

PARTICIPANTS

Two hundred consecutive patients undergoing OCT imaging.

METHODS

One eye (primary) from each of 200 consecutive patients undergoing Stratus OCT imaging (Carl Zeiss Meditec, Dublin, CA) with radial lines or fast macular thickness-based acquisition protocols was selected for review by 2 graders. On each of the line scans, graders evaluated the position of the automated retinal boundary lines (inner retinal surface and retinal pigment epithelium band) used by the OCT machine for thickness calculations and graded the positioning on a 6-point subjective, categorical error scale to generate an error score. The presence of thickness errors was correlated with various parameters, including the analysis confidence assessment reported by the OCT software, disease diagnosis, retinal morphologic features, the foveal center thickness standard deviation (FCTSD), and the FCTSD-to-foveal center thickness (FCT) ratio.

MAIN OUTCOME MEASURE

Average OCT retinal thickness error score.

RESULTS

Errors of retinal boundary detection and thickness measurement were observed in 92% of eyes, but were severe in only 13.5% of eyes. The identification of an error or low analysis confidence by the OCT software was strongly associated with the severity of the retinal thickness errors. A higher FCTSD-to-FCT ratio and presence of subretinal fluid also were associated with more severe errors. Retinal cysts and a diagnosis of retinal vascular disease such as diabetic macular edema were less likely to be associated with significant errors.

CONCLUSIONS

Retinal thickness measurement errors occur frequently with current OCT segmentation and analysis algorithms. Severe errors are more frequent in eyes with subretinal pathologic features, but generally are detected by the OCT software. A high FCTSD-to-FCT ratio (>0.1) also may alert the clinician to the possibility of thickness errors. Clinical studies, particularly those pertaining to subretinal diseases, should consider these errors when incorporating OCT imaging in the study design.

The epidemiology of giant cell arteritis : a 12-year retrospective study

OBJECTIVE

To study the incidence of biopsy-proven giant cell arteritis (GCA) in a Hispanic population with clinical features suggestive of GCA.

DESIGN

Retrospective review.

PARTICIPANTS

Records of 121 consecutive patients who underwent temporal artery biopsy at the Doheny Eye Institute and the Los Angeles County/University of Southern California Hospital from January 1986 through April 1998 were reviewed.

MAIN OUTCOME MEASURES

The incidence of biopsy-proven GCA was determined, and the biopsy-positive group was compared with the biopsy-negative group. Study variables included age at diagnosis, gender, erythrocyte sedimentation rate (ESR), and ethnic background.

RESULTS

Among these 121 patients who underwent temporal artery biopsy, the mean age of those in the biopsy-positive group (75.2 +/- 5.0 years) was higher than that of those in the biopsy-negative group (69.1 +/- 9.2 years; P < 0.0001). There was no statistical correlation between biopsy-positive and biopsy-negative groups for gender or ESR level, but ESR was statistically significant for whites when we controlled for race. Nineteen of 66 white patients (29%) had positive biopsy results, whereas only 1 of the 9 Asian patients (11%) none of the 40 Hispanic patients (0%; P < 0.0001) and none of the 6 African American patients (0%) had positive biopsy results.

CONCLUSIONS

Giant cell arteritis occurs primarily in the white population. None of the Hispanic patients in our study was found to have positive biopsy results. Hispanic persons may have unknown factors that protect them from this disease. Further study is necessary to examine the genetic predisposition.

Complications and prognostic factors in Vogt-Koyanagi-Harada disease

PURPOSE

To identify associations between complications of disease and final visual acuity in patients with Vogt-Koyanagi-Harada disease and to identify prognostic factors for disease outcome.

METHODS

All patients diagnosed with Vogt-Koyanagi-Harada disease at the Doheny Eye Institute or the Los Angeles County/University of Southern California Medical Center between 1983 and 1997 were reviewed. Data extracted included initial and final visual acuities, age, gender, ethnicity, complications, treatment, duration of disease, and number of recurrences.

RESULTS

One hundred one patients with Vogt-Koyanagi-Harada disease were identified, 68 (67%) of which were female. Mean age was 34 +/- 14 years (range, 8 to 75 years). Asians presented at a significantly older age than all other groups. One hundred three eyes (51%) developed at least one complication, including cataract in 84 eyes (42%), glaucoma in 54 eyes (27%), choroidal neovascular membranes in 22 eyes (11%), and subretinal fibrosis in 13 eyes (6%). Patients who developed at least one complication had a significantly longer median duration of disease and number of recurrent episodes of inflammation (P =.0001 for each) than did those patients who developed no complications. Statistically significant associations existed between poor final visual acuity and greater numbers of complications (P =.001), greater age at onset (P =.03), a longer median duration of disease (P =.03), and greater number of recurrent episodes of inflammation (P =.0004). Eyes possessing a better visual acuity at presentation were more likely to have a better visual acuity at final follow-up (P =.001).

CONCLUSIONS

Factors associated with a worse final acuity included increasing numbers of complications, greater age at onset, and worse acuity at presentation.

The effectiveness of a topical antibiotic irrigating solution in a model of staphylococcal keratitis after lamellar keratectomy

PURPOSE

To create a model of Staphylococcus aureus keratitis after lamellar keratectomy; to assess the toxicity of an antibiotic irrigating solution on the corneal stromal bed; and to test the chemotherapeutic effectiveness of a topical antibiotic, both alone and with an antibiotic-containing irrigating solution in preventing S. aureus keratitis after lamellar keratectomy.

METHODS

The right eye of each of 38 rabbits were used in this study. In 18 eyes, a lamellar flap was created with a microkeratome, and an inoculum of S. aureus (either 1,000, 5,000, or 50,000 CFUs) was instilled under each flap; the eyes were examined for signs of infection and inflammation at 24 and 48 hours. In another five eyes, a lamellar flap was created in the same manner and the stromal bed was irrigated with 0.3% ofloxacin; the eyes were assessed for ocular inflammatory changes and evidence of crystalline deposits. Finally, in each of 15 additional eyes, 1,000 CFUs of S. aureus were instilled under a lamellar flap to create experimental infectious keratitis. The keratitis was treated according to three regimens: irrigation of the stromal bed with sterile balanced salt solution; irrigation of the stromal bed with 0.3% ofloxacin, followed by application of topical ofloxacin four times a day; application of topical ofloxacin only, four times a day. Eyes were examined for infection and ocular inflammatory changes at 24 and 48 hours.

RESULTS

Staphylococcus aureus keratitis can consistently be produced under the stromal flap by inoculation of relatively few organisms. Irrigation of the stromal bed with commercial-strength topical ofloxacin does not appear to be toxic to the stromal bed, with no evidence of crystalline precipitates of the antibiotic. In our model of infectious keratitis after lamellar keratectomy, both topical ofloxacin alone and the combination of topical ofloxacin and irrigation of the stromal bed with 0.3% ofloxacin were effective at preventing S. aureus keratitis. However, the combined treatment of antibiotic irrigation plus topical antibiotic was more effective at preventing inflammation than topical ofloxacin alone.

CONCLUSIONS

In this model of S. aureus keratitis after lamellar keratectomy, irrigation of the stromal bed with antibiotic plus topical antibiotic appears to be both safe and effective for preventing infection.

Randomized clinical trial of the 350-mm2 versus the 500-mm2 Baerveldt implant: longer term results: is bigger better?

OBJECTIVE

To report the longer term results of a randomized, clinical trial comparing the 350-mm2 and the 500-mm2 Baerveldt glaucoma implants.

DESIGN

Extended follow-up on a randomized, controlled trial.

PARTICIPANTS

Between March 1991 and April 1993, 107 patients with uncontrolled intraocular pressure (IOP) due to non-neovascular glaucoma associated with aphakia, pseudophakia, or failed filters were randomly assigned for surgical placement of either the 350-mm or the 500-mm2 Baerveldt implant at the Doheny Eye Institute.

METHODS

A random-numbers table was used to assign each patient to one of the two groups. Preoperative IOPs and visual acuities were recorded. Clinical records were reviewed to ascertain postoperative IOPs, visual acuities, number of medications used, and implant-related complications that occurred throughout the follow-up period.

MAIN OUTCOME MEASURES

Success was defined as IOP of 6 mmHg or greater and of 21 mmHg or less in two or more consecutive follow-up visits without further glaucoma surgery or loss of light perception attributable to glaucoma.

RESULTS

The overall success rates were 87% for the 350-mm2 group and 70% for the 500-mm2 group (P = 0.05). Average follow-up was 37 months (range, 1-76 months) for the 350-mm2 group and 34 months (range, 5-77 months) for the 500-mm2 group. The life-table success rates declined over time for both implant groups, from a high of 98% for the 350-mm2 group and 92% for the 500-mm2 group at 1 year to a cumulative success rate of 79% for the 350-mm2 group and 66% for the 500-mm2 group at 5 years. Visual acuities were better or remained the same in 50% of the patients in the 350-mm2 group and 46% of those in the 500-mm2 group. Complications during the 5-year follow-up were also statistically similar.

CONCLUSIONS

The longer term results show that the 350-mm2 Baerveldt implant is more successful than the 500-mm2 implant for overall IOP control. Interval comparisons indicate a higher rate of success for the 350-mm2 implant in the first, second, third, fourth, and fifth years of implantation. Visual acuities, implant-related complications, and average IOPs were statistically indistinguishable between the two groups.

Photorefractive keratectomy in African Americans including those with known dermatologic keloid formation

PURPOSE

To report the outcome of photorefractive keratectomy in African Americans, including those with a known history of dermatologic keloid formation.

METHODS

A retrospective analysis of African American patients who had photorefractive keratectomy at either of our institutions was undertaken to identify all patients who were at least 3 months status-post refractive surgery. The presence or absence of a history of keloid formation, as well as preoperative and postoperative measurements of uncorrected visual acuity, best-corrected visual acuity, manifest refraction, and the presence and magnitude of any postoperative corneal haze were analyzed.

RESULTS

Twelve patients (19 eyes) met the inclusion criteria and three of these patients (six eyes) had a history of keloid formation. Mean uncorrected visual acuity +/- SD for the entire study group improved from 20/369 +/- 20/270 preoperatively to 20/19.4 +/- 20/7.1 postoperatively (average follow-up, 13.8 months). All eyes had postoperative uncorrected visual acuity of 20/40 or better; 14 (74%) achieved 20/20 or better. Mean best spectacle corrected visual acuity went from 20/14.8 +/- 20/2.8 preoperatively to 20/15.5 +/- 20/3.2 postoperatively (not statistically significant). Mean manifest spherical equivalent was -4.9 +/- 3.4 diopters preoperatively and +0.03 +/- 0.55 diopters postoperatively. Eight eyes (42%) had trace to 1+ corneal haze following photorefractive surgery. A comparison of postoperative uncorrected and best-corrected visual acuities of known keloid formers with nonkeloid formers revealed no significant statistical difference.

CONCLUSIONS

African Americans may have excellent visual outcomes following photorefractive keratectomy. History of keloid formation does not appear to have an adverse effect on the outcome. These results question whether known dermatologic keloid formation should be a contraindication to photorefractive keratectomy.

Post-ICU mechanical ventilation: treatment of 1,123 patients at a regional weaning center

STUDY OBJECTIVES

To update our database, reporting changes in the results of weaning attempts and profile of patients transferred to us after prolonged mechanical ventilation (PMV) in the ICU.

DESIGN

Retrospective record review, with prospective recording of physiologic measurements on admission from mid-1994.

SETTING

Regional weaning center (RWC).

PATIENTS

We studied 1,123 consecutive ventilator-dependent patients transferred for attempted weaning over an 8-year period.

MEASUREMENTS AND RESULTS

Median (range) time of mechanical ventilation prior to transfer to the RWC declined from 37 (1 to 249) days in 1988 to 29 (1 to 120) days in 1996 (p<0.05). Acute physiology score of acute physiology and chronic health evaluation (APACHE) III was 32 (6 to 123) on RWC admission, equaling reported scores soon after ICU admission. Comparing other data on admission from 1988 to 1996, mean (+/-SD) serum albumin level declined from 2.92+/-0.58 to 2.43+/-0.50 g/dL, and alveolar-arterial oxygen pressure difference widened from 106+/-50 to 139+/-99 mm Hg. Prevalence of stage II or worse pressure ulceration on admission increased from 34% in 1988 to 46% in 1995. Despite these trends, there has been no significant change in patient outcome (55.9% weaned, 15.6% failed to wean, 28.8% died) or in median time to wean (29 [1 to 226] days). Overall survival at 1 year after discharge for the 8-year period is 37.9%, improving from 29% in 1988-1991 to 45% since 1992; survival in weaned patients discharged to home has improved from 45 to 59% during the respective time periods.

CONCLUSIONS

Patients are being transferred from the ICU to our RWC for attempted weaning sooner in their course of PMV. Although more severely ill on arrival than in past years, mortality is unchanged, more than half of the patients continue to be successfully weaned, and survival after RWC discharge is improved.

Sensitivity, specificity, and predictive values of screening tests for eye conditions in a clinic-based population

PURPOSE

To assess four commonly available visual function tests to detect visually disabling or vision-threatening eye conditions among new patients of a large, urban, public, general ophthalmology clinic.

METHODS

Three hundred seventeen patients were tested for contrast sensitivity, Amsler grid abnormalities, and visual acuity at near and at distance. A complete eye evaluation found the prevalence of serious eye diseases, allowing determination of the sensitivity (Sn), specificity (Sp), likelihood ratio (LR), and other characteristics of each test.

RESULTS

Of 317 patients, most were Hispanic (77%), women (60%), and middle-aged (44 +/- 17 years). Normal findings were reported in 18%; refractive error in 43%; cataracts in 16%; glaucoma in 7.3%; and macular degeneration in 4.1%. Near visual acuity of 20/40 or worse (Sn = 0.75; Sp = 0.74; LR = 2.8); and distance visual acuity testing of 20/30 or worse (Sn = 0.74; Sp = 0.73; LR = 2.7) correlated significantly with ocular disease, whereas contrast sensitivity testing (Sn = 0.62; Sp = 0.41; LR = 1.1) and Amsler grid test (Sn = 0.19; Sp = 0.92; LR = 2.4) did not. Test performance decreased when refractive errors were excluded and among those younger than 40 years of age relative to those 40 years of age or older.

CONCLUSION

Of the four screening tests studied, distance and near threshold visual acuities as defined above were judged to have the best correlations of an abnormal result with ocular disease, both including or excluding refractive error. Different combinations of tests did not result in more accurate detection of ocular disease. More efficient screening tools for detecting ocular disease need to be developed.

Corneal sensitivity and burning sensation. Comparing topical ketorolac and diclofenac

OBJECTIVES

To compare the effect of topical 0.5% ketorolac tromethamine and 0.1% diclofenac sodium on human corneal sensitivity and to assess the intensity of burning sensation at specific intervals after drop instillation.

DESIGN AND SETTING

Double-masked parallel clinical study.

PATIENTS

Eleven women and 4 men (8 white, 4 Hispanic, 3 Asian), 22 to 60 years of age (mean [ +/- SD], 34 +/- 10 years).

INTERVENTIONS

Repeated instillation of either ketorolac and placebo or diclofenac and placebo at 5-minute intervals.

MAIN OUTCOME MEASURES

Assessment of corneal sensitivity before instillation, immediately after instillation, and after termination of drop application; and subjective evaluation of burning sensation by asking participants to rate burning on a scale ranging from 0 (none) to 3 (severe) after each drop application.

RESULTS

Both diclofenac (P < .01) and ketorolac (P < .01) decreased corneal sensitivity significantly, while the placebo had no measurable effect. After administration of additional drops over time, the effect of diclofenac and ketorolac increased. After termination of the drug instillation, corneal sensitivity returned to baseline significantly slower (P < .01) in participants receiving diclofenac than in those receiving ketorolac. Ketorolac (P = .01) and diclofenac (P < .05) were significantly more effective in whites than in nonwhites. Mean burning sensation was mild, and there was no statistically significant difference between the 2 drugs on this measure (P = .12).

CONCLUSIONS

The decrease in corneal sensitivity in normal human corneas is more pronounced and longer lasting with diclofenac than with ketorolac. Both drugs are well tolerated topically and may be useful for pain reduction after refractive corneal surgery.

Use of the ganciclovir implant in the treatment of recurrent cytomegalovirus retinitis

OBJECTIVE

To evaluate the efficacy of the ganciclovir implant in the treatment of recurrent cytomegalovirus (CMV) retinitis.

METHODS

Patients with acquired immunodeficiency syndrome and recurrent CMV retinitis were evaluated for entry into the study. A ganciclovir implant was inserted in 91 eyes of 70 patients between October 1992 and October 1995. The efficacy of the implant and visual results were retrospectively reviewed.

RESULTS

Fifty-three (76%) of 70 eyes had inactive CMV retinitis 1 month postoperatively (positive initial response). Twenty-one eyes of 19 patients had less than 1 month of follow-up. Nineteen (36%) of 53 eyes developed recurrent CMV retinitis. The median time to recurrence for those patients with a positive initial response was 7 months. Forty-eight (84%) of 57 patients with follow-up longer than 1 month after implant insertion in the first eye received systemic anti-CMV medication during the study. The cumulative risk for developing a retinal detachment was 23% at 6 months following implant insertion. Other complications included vitreous hemorrhage, hyphema, and suprachoroidal implantation of the device.

CONCLUSION

The ganciclovir implant is effective as an adjunct to continued systemic therapy in those patients with recurrent CMV retinitis.

Choroidal hypoperfusion after surgical excision of subfoveal neovascular membranes in age-related macular degeneration

PURPOSE

To study the choroidal circulation after surgical excision of subfoveal choroidal neovascular membranes (SFCNVM) in age-related macular degeneration (ARMD).

METHODS

Twelve eyes of eleven patients with ARMD that underwent surgical excision of SFCNVMs were evaluated with stereoscopic color fundus photography, stereoscopic fluorescein angiography (FA) and scanning laser ophthalmoscope-indocyanine green videoangiography (SLO-ICGv). The patients were followed for a mean of 7.9 months (range 2 to 14 months).

RESULTS

Preoperatively, all eyes had angiographic evidence of a SFCNVM, with SLO-ICGv showing the presence of a choriocapillary blush. Postoperatively, stereoscopic color fundus photographs documented that the bed of the surgical excision was characterized by an absence of visible retinal pigment epithelial (RPE) pigmentation in all eyes. Stereoscopic FA of the excision bed revealed choriocapillary hypofluorescence with visible dye perfusion in the underlying medium and large choroidal vessels in all eyes. SLO-ICGv of the excision bed disclosed the presence of perfused medium and large choroidal vessels, but a marked choroidal hypofluorescence with loss of the choriocapillary and small choroidal vascular filling within the excision bed in eleven of the twelve eyes.

CONCLUSION

Our results indicate that both choriocapillary and small choroidal vascular filling is frequently abnormal or absent in the bed of surgically excised subfoveal neovascular membranes in ARMD. This finding, which may represent either pathologic or iatrogenic choriocapillary and small choroidal vascular atrophy or occlusion with preservation of perfusion in the underlying medium and large choroidal vessels, may influence structural and visual recovery after submacular surgery for ARMD, despite RPE transplantation or regeneration.

The importance of initial management in the treatment of severe infectious corneal ulcers

PURPOSE

To identify factors that influence the outcome of patients with severe infectious corneal ulcers.

METHOD

A retrospective review was performed of the hospital records of all such patients admitted to the Doheny Eye Hospital during a 30 month period. Outcome variables examined were change in visual acuity, duration of hospitalization, hospital charges, and percentage of patients who required penetrating keratoplasty.

RESULTS

Sixty-two ulcers were included. An organism was identified and antibiotic sensitivities established in 52 patients (84%). Inpatient therapy involved a combination of fortified aminoglycoside and cephalosporin antibiotics in 39 patients (63%) and was found to be appropriate on the basis of sensitivity studies in 49 (94%) of 52 patients. Inappropriate initial treatment was related to increased hospital charge (P = 0.024) as well as increased risk of penetrating keratoplasty (P = 0.001).

CONCLUSIONS

Appropriate initial therapy is most critical in the course of serious corneal ulcers, and aggressive, broad-spectrum antibiotic coverage is advocated.

A randomized trial comparing mitomycin C and conjunctival autograft after excision of primary pterygium

PURPOSE

To determine the rate of recurrence and complications after bare sclera excision of primary pterygia followed by low-dose mitomycin C (0.2 mg/ml twice daily for five days), placebo (balanced saline solution), or conjunctival autograft.

METHODS

We performed a prospective, double-masked clinical trial of 64 patients (60 Hispanic) randomly assigned to a treatment group. Twenty-four patients received mitomycin C, 23 conjunctival autograft, and 17 placebo. Recurrence was defined as fibrovascular tissue over the corneoscleral limbus onto clear cornea in the area of previous pterygium excision.

RESULTS

The recurrence rate after mitomycin C and conjunctival autograft was 38% and 39% of eyes, respectively, after mean follow-up (in recurrence-free patients) of 12.3 and 13.5 months, respectively. The recurrence rate after placebo treatment was significantly higher (P = .002), 88%, after mean follow-up (in recurrence-free patients) of 9.3 months. Increasing age was associated with significantly fewer recurrences (P = .006) after controlling for pterygium type (atrophic, noninflamed, or inflamed) and treatment group. The mean time to recurrence varied from 3.7 to 4.8 months; only 6% of recurrences were noted after the sixth postoperative month. Major complications included symblepharon (two), loose autograft (one), and pyogenic granuloma (two). No group had significantly more complications.

CONCLUSIONS

Conjunctival autograft and low-dose topical mitomycin C are equally effective as adjunctive treatment after excision of primary pterygia in this young, southern California, predominantly Hispanic population. Both methods have significantly lower rates of recurrence than bare sclera excision alone, and neither is associated with severe complications after one year of follow-up. Increasing patient age is associated with significantly less risk of recurrence.

Microorganisms cultured from the anterior chamber of ruptured globes at the time of repair

PURPOSE

We studied events leading to the development of posttraumatic endophthalmitis by examining the significance of 15 factors on microbial contamination of injured eyes.

METHODS

A prospective study was done of 30 ruptured globes in patients admitted to an urban medical center. Cultures were taken from the conjunctiva before and after preoperative disinfection and from the anterior chamber at the beginning and end of wound repair. Twenty-five of 30 patients received a three-day regimen of intravenous antibiotics that were begun before surgery.

RESULTS

Anterior chamber samples grew microorganisms in ten (33%) of 30 eyes, with positive cultures recovered from specimens taken at the beginning of wound repair in eight eyes and at the end of wound repair in six eyes. Contamination with indigenous flora may have occurred at the time of injury in one eye and during repair in another eye. Microbes recovered included Staphylococcus, Corynebacterium, and Aspergillus species. No patient developed endophthalmitis. Of the 15 factors studied, only intravenous antibiotics significantly decreased the incidence of positive anterior chamber cultures in eyes treated before wound repair compared with eyes not receiving such therapy (P = .002).

CONCLUSIONS

Despite the frequency of anterior chamber microbial contamination during injury or repair of the wound, with our treatment protocol and the presence of physiologic mechanisms to reduce intraocular microbes, no eyes developed clinical endophthalmitis. With our limited sample size only intravenous antibiotic therapy was found significantly to reduce anterior chamber microorganisms at the time of surgical repair, supporting their prophylactic use against the development of posttraumatic endophthalmitis.

Evidence of subtypes of Alzheimer's disease and implications for etiology

OBJECTIVE

Because age of onset does not reliably define two subtypes of Alzheimer's disease, classification based on the severity of neuronal degeneration was tested.

DESIGN

Numbers of extracellular tangles and pyramidal neurons in the hippocampus were used to group patients.

PATIENTS

The study population consisted of 46 elderly patients satisfying DSM-III criteria for dementia and NINCDS-ADRDA criteria for definite Alzheimer's disease after death.

RESULTS

Univariate logistic regression analysis showed the numbers of neurofibrillary tangles and pyramidal neurons and the duration of dementia were significantly associated with grouping based on the presence of abundant extracellular tangles. Ninety-one percent of patients were correctly classified as compared with 85% correctly classified by age of onset data. Odds ratios showed that increasing numbers of neurofibrillary tangles predicted greater severity of neuronal loss.

CONCLUSION

The results of the study indicate the importance of neurofibrillary degeneration, not the deposition of amyloid, in the pathogenesis of Alzheimer's disease. They support a classification of Alzheimer's disease related more closely to the severity of neurofibrillary degeneration than to age at onset.