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Biomedical subjects

David J Apple

Publications and source records attributed to David J Apple.

At least 73 records · Page 4Linked to original sources
PubMed2002

Snowflake degeneration of polymethyl methacrylate posterior chamber intraocular lens optic material: a newly described clinical condition caused by unexpected late opacification of polymethyl methacrylate.

OBJECTIVE: To report 25 cases of gradual, but sometimes progressive, late-postoperative degeneration of polymethyl methacrylate (PMMA) optics of posterior chamber (PC) intraocular lens (IOL) implants, often resulting in a clinically significant visual decrease long after the implantation, sometimes to a severity that required IOL explantation/exchange. DESIGN: Analysis of explanted PC IOLs, clinical histories, and photographs. PARTICIPANTS: We analyzed 25 case histories/photographs and/or explants from 18 patients implanted in the 1980s to mid-1990s with three-piece PC IOLs with PMMA optics and with polypropylene or PMMA haptics. The IOL optic from each case had characteristic snowflake or crystalline opacifications. This condition occurred with more than one manufacturer and in some cases was restricted to certain lot numbers. METHODS: The explanted IOLs (n = 10) were studied by gross inspection and by light and scanning electron microscopy, as well as confocal and energy dispersive spectroscopy. MAIN OUTCOME MEASURES: The snowflake lesions were noted within the IOL optics. The nature of these lesions was investigated. RESULTS: Assimilation of clinical information with pathologic and morphologic profiles of all cases suggested that the snowflake opacification was a small spherical lesion surrounded by an outer pseudocapsule composed of compressed, degenerated PMMA, with a central core containing convoluted fragments of PMMA. The lesions were classified into four clinical and pathologic grades according to their density and severity. CONCLUSIONS: This is the first clinicopathologic correlative report on this complication. We postulate that manufacturing variations in some IOL models fabricated in the 1980s and early 1990s are responsible. The snowflake lesions seem to represent a destruction of the PMMA material. The cluster of lesions in implanted lenses manufactured by Surgidev was less progressive than some other models, including lenses made by IOPTEX Research Corporation. This identification of a condition previously unreported is important to alert clinicians regarding these perplexing lesions that may otherwise be considered idiopathic, with no obvious clinical hint as to their origin. The prevalence noted thus far is still too low to in any way suggest that this condition would occur in 100% of PMMA IOLs from these manufacturers. However, these late-occurring lesions, present in lens models that were implanted in hundreds of thousands of patients in the last decade or so, could have constituted a true epidemic, except that many of the patients are now deceased.

Device Removal↗
PubMed2002

Hydrophilic acrylic intraocular lens optic and haptics opacification in a diabetic patient: bilateral case report and clinicopathologic correlation.

OBJECTIVE: To report clinicopathologic and ultrastructural features of two opacified single-piece hydrophilic acrylic intraocular lenses (IOLs) explanted from a diabetic patient. DESIGN: Interventional case report with clinicopathologic correlation. SETTING: A 64-year-old white female underwent phacoemulsification and implantation of a single-piece hydrophilic acrylic lens (SC60B-OUV; Medical Developmental Research, Inc., Clear Water, FL) in October 1998 in the left eye and in July 1999 in the right eye. The best-corrected visual acuity after surgery was 20/60 in the left eye and 20/50 in the right eye. The patient had a marked decrease in visual acuity in June 2000 as a result of a milky, white opalescence of both lenses. Intraocular lens explantation and exchange was performed in both eyes and the explanted IOLs were submitted to our center for detailed pathologic, histochemical, and ultrastructural evaluation. They were stained with alizarin red and the von Kossa method for calcium, and also underwent scanning electron microscopy and energy dispersive radiograph spectroscopy to ascertain the nature of the deposits leading to opacification. MAIN OUTCOME MEASURES: Documentation of calcium deposits confirmed by histochemical stains and surface analyses. RESULTS: Opacification of the IOL was found to be the cause of decreased visual acuity. The opacification involved both the IOL optic and the haptics in the left eye and was confined to the IOL optic in the right eye. Histochemical and ultrastructural analyses revealed that the opacity was caused by deposition of calcium and phosphate within the lens optic and haptics. CONCLUSIONS: There are two features that distinguish this case from those reported earlier. This is the first clinicopathologic report of lens opacification that has involved completely the lens optic and the haptics. Second, these two explanted IOLs document the first bilateral case. This process of intraoptic and haptic opacification represents dystrophic calcification of unknown cause. Diabetic patients appear to be more severely and more often affected by lens opacification. Long-term follow-up of diabetic patients implanted with this IOL design should be maintained by surgeons and manufacturers.

Acrylic Resins↗
PubMed2002

Epithelial downgrowth after clear cornea phacoemulsification: report of two cases and review of the literature.

OBJECTIVE: To report two cases of diffuse epithelial downgrowth after clear cornea phacoemulsification and to review the different treatment options for this ominous disease. DESIGN: Two interventional case reports. METHODS: Retrospective review of two eyes from two different patients in whom epithelial downgrowth developed 7 and 3 months after uneventful clear cornea phacoemulsification. In the first case, the epithelial invasion seemed to be growing from the temporal incision site onto the corneal endothelium toward the visual axis. Cryotherapy was applied to the affected cornea, with control of the growing membrane. A penetrating keratoplasty was performed to restore visual function. In the second patient, the membrane was attached to the iris and posterior cornea and was confirmed by diagnostic argon laser photocoagulation. This case was surgically treated with en bloc excision and a corneoscleral graft. MAIN OUTCOME MEASURES: Visual acuity at the final follow-up visit. RESULTS: Surgical treatment of the epithelial downgrowth was different for both patients. In the postoperative period, a best-corrected visual acuity of 20/60 and 20/30 was achieved in each case. No regrowth of the membrane was observed. CONCLUSIONS: Treatment of epithelial downgrowth is controversial. We present two cases of epithelialization of the anterior chamber with either clinical or histologic confirmation after clear cornea sutureless phacoemulsification. Surgical treatment should be attempted promptly to obtain a good visual prognosis.

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PubMed2002

Intracapsular ring sustained 5-fluorouracil delivery system for the prevention of posterior capsule opacification in rabbits: a histological study.

PURPOSE: To evaluate the efficacy of an intracapsular ring releasing 5-fluorouracil (5-FU) in preventing posterior capsule opacification (PCO) in rabbit eyes. SETTING: Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA, and Chu Morvan, Department d'Ophtalmologie, University of Brest, France. METHODS: Seventeen rabbits were divided into 3 groups: Group 1, 6 rabbits (6 eyes), had phacoemulsification only (control group); Group 2, 6 rabbits (6 eyes), had phacoemulsification with implantation of an open-loop hydrogel intracapsular ring; Group 3, 5 rabbits (5 eyes), had phacoemulsification with implantation of a ring with sustained release of 0.25 microg/h of 5-FU for 9 days. All eyes were followed for 8 weeks before enucleation. Capsular bag shrinkage and the position of the intracapsular ring were assessed, and central and peripheral PCO was evaluated for intensity and area by stereomicroscopy from a posterior (Miyake-Apple) view. The residual equatorial lens epithelial cells (LECs) were counted by the same observer in histological sections. Transmission electron microscopy (TEM) of the cornea, capsular bag, and retina was done to evaluate the toxicity of 5-FU. RESULTS: No significant difference was seen in the degree of capsular bag shrinkage in the 3 groups. The intracapsular ring was decentered in 2 eyes (1 each in Groups 2 and 3). There was a statistically significant difference (P <.05, Student t test) between Group 1 and Groups 2 and 3 in the area and intensity of central PCO. There was no difference between Groups 2 and 3 in the intensity of central PCO. No evidence of 5-FU toxicity to intraocular structures (cornea, capsular bag, and retina) was demonstrated on TEM analysis. CONCLUSION: Implantation of an intracapsular ring may prevent central PCO after cataract surgery by mechanically blocking LEC migration toward the central visual axis. The potential pharmacological effect of 5-FU in PCO prevention was not demonstrated.

Animals↗
PubMed2002

Effect of hydrodissection on intraoperative performance: randomized study.

PURPOSE: To evaluate the effect of hydrodissection on intraoperative performance during phacoemulsification of age-related nuclear cataracts. SETTING: Iladevi Cataract & IOL Research Centre, Ahmedabad, India, and Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA. METHODS: In a prospective study, 86 eyes were randomly assigned to have multiquadrant hydrodissection (+HD, n = 48) or no hydrodissection (-HD, n = 38) during phacoemulsification of a grade 1 to 3 nuclear cataract. Excluded were patients with grade 4 or 5 nuclear sclerosis, a poorly dilating pupil, or associated ocular/systemic disease. Parameters assessed were nucleus and cortex removal time, the amount of fluid used for cortex removal, and the total amount of fluid used. The ease of nucleus rotation and cortical cleanup was also evaluated and graded subjectively as very easy, difficult, or very difficult. Data were analyzed using the Student t test and the chi-square test. RESULTS: The mean nucleus removal time was 355 seconds +/- 237 (SD) and 474 +/- 212 seconds in the +HD and -HD groups, respectively (P =.09). The mean cortex removal time was significantly less in the +HD group than in the -HD group (79 +/- 51 seconds and 220 +/- 222 seconds, respectively) (P =.007). Significantly less fluid (43%) was used for cortex removal in the +HD group than in the -HD group (mean 70 +/- 45 mL and 123 +/- 82 mL, respectively) (P =.013), and significantly less total fluid (35%) was used in the +HD group (312 +/- 132 mL and 422 +/- 80 mL, respectively) (P =.002). Nucleus rotation was easy in all eyes in the +HD group; 68.43% of eyes in the -HD group failed to achieve rotation (P =.001). Cortex removal was very easy in 52.08% of eyes in the +HD group and easy in 47.90%; it was easy in 52.63% in the -HD group, difficult in 36.84%, and very difficult in 10.52%. CONCLUSION: The use of multiquadrant cortical-cleaving hydrodissection made removal of the lens nucleus and cortex easier and faster during phacoemulsification of age-related nuclear cataracts.

Dissection↗
PubMed2002

Bipseudophakia: clinicopathological correlation of a dropped lens.

PURPOSE: To examine postmortem human globes containing an anterior chamber and a posterior chamber intraocular lens (IOL). SETTING: Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Charleston, South Carolina, USA. METHODS: The globes were sectioned at the equator, and the anterior and posterior segments were macroscopically examined. Gross photographs were taken using the Miyake-Apple posterior photographic technique. Histological sections were cut and stained with hematoxylin and eosin, periodic acid-Schiff, and Masson's trichrome. RESULTS: Histopathological findings included a large Soemmering's ring, a tear in the posterior capsule, 1 haptic of the anterior chamber IOL displaced into the iridectomy, thin and atrophic corneal epithelium, separation of Bowman's layer and stroma by fibrovascular tissue, and atrophy of the retinal ganglion cell layer and nerve fiber layer. CONCLUSION: In cases in which secondary IOL implantation is indicated, removing the dislocated IOL appears to be a reasonable choice.

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PubMed2002

Refractive Surgery Survey 2001.

In February 2001, a questionnaire on the practice of refractive surgery was sent worldwide to all 8196 members of the American Society of Cataract and Refractive Surgery; 1511 responses (18.4%) were received. Although laser in situ keratomileusis (LASIK) was the most common refractive procedure reported, phakic intraocular lenses, clear lens extraction, and photorefractive keratectomy were also widespread. Nineteen percent of the respondents said they had had refractive surgery, and that group reported performing significantly more procedures than those who had not had a refractive procedure (P < .0001). The most common complication of LASIK was dry eyes, occurring in more than half of the cases in one fourth of the practices; however, only 30% of surgeons said they perform a Schirmer test before surgery. High-volume surgeons reported seeing fewer cases of flap striae (P = .002) and slipped flaps (P = .02) than low-volume surgeons. Seventy-seven percent said that wavefront LASIK ablation will increase the quality of vision and of those already performing wavefront ablation, 92% stated they believe it will improve outcomes.

Adult↗
PubMed2002

Endothelial decompensation after laser in situ keratomileusis.

We report the results of laser in situ keratomileusis (LASIK) in a 58-year-old woman with a history of corneal guttata in the right eye and mild Fuchs' dystrophy in the left eye. Preoperative pachymetry was 586 microm and 656 microm, respectively. The surgical treatment was +1.50 diopters (D) in the right eye and +3.25 D in the left eye. Surgery was performed using a VISX S2 Star laser and a Hansatome microkeratome with a 9.5 mm ring. Postoperatively, edema in the right eye resolved and pachymetry returned to 585 microm, but the left cornea decompensated despite maximum medical therapy and had a final pachymetry of 779 microm. The patient was referred to our cornea service for penetrating keratoplasty, which was performed 14 months after the LASIK treatment.

Corneal Diseases↗
PubMed2002

Permanent blue discoloration of a hydrogel intraocular lens by intraoperative trypan blue.

A 79-year-old white man had cataract surgery in the right eye with implantation of an Acqua intraocular lens (IOL) (Mediphacos). Trypan blue 0.1% was used during surgery to stain the anterior capsule and enhance the contrast during capsulorhexis. Seven days after surgery, the patient presented with "dark and double" vision (monocular diplopia). The IOL was decentered superiorly and appeared dark blue. The lens was explanted 2 months after surgery and sent for gross and microscopic analyses in a dry state and after hydration. The same analyses were performed on 2 unused lenses of the same design that had been immersed in diluted trypan blue solutions (0.01% and 0.001%). On the explanted lens, the dark blue staining was denser in the optic, especially in its periphery. The blue discoloration could not be removed after 24 hours of lens immersion in a balanced salt solution at 37 degrees C. Permanent staining of the unused lenses was also obtained after immersion in the trypan blue solutions.

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PubMed2002

Effect of haptic angulation on posterior capsule opacification in modern foldable lenses with a square, truncated optic edge.

PURPOSE: To analyze the effect of different haptic angulations on posterior capsule opacification (PCO) in a modern foldable intraocular lens (IOL) with a square-edged optic designed to reduce the incidence of PCO. SETTING: Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA. METHODS: Ten Dutch Belted, serum Pasteurella-free pigmented rabbits of the same age and sex had bilateral phacoemulsification with endocapsular IOL implantation. The eyes were implanted with Centerflex IOLs (Rayner) with haptic angulations of 0 degree (n = 8), 5 degrees (n = 4), 10 degrees (n = 4), or 15 degrees (n = 4). RESULTS: There was no statistical difference in central PCO, peripheral PCO, and measured IOL decentration among the angulation groups. CONCLUSION: With the Centerflex IOL, haptic angulation did not seem to be a significant factor influencing PCO. It appears that the barrier effect of the IOL's truncated, square-edged optic overrides the angulation factor in preventing PCO.

Animals↗
PubMed2002

Rates and causes of intraoperative removal of foldable and rigid intraocular lenses: clinicopathological analysis of 100 cases.

PURPOSE: To analyze the rates of and reasons for intraoperative explantation of foldable and rigid intraocular lenses (IOLs) to determine the complication profile of each IOL design. SETTING: Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA. METHODS: The study comprised data analysis of foldable (n = 85) and rigid (n = 15) IOL specimens that were explanted immediately after primary implantation. RESULTS: Eighty-five foldable intraoperative explants were accessioned. These comprised 14.5% of the 586 foldable IOL explants received between January 1988 and September 2000. There were 15 rigid poly(methyl methacrylate) (PMMA) intraoperative explants out of 2077 rigid explant specimens (0.7%). Fifty-one (60%) of the foldable IOLs requiring intraoperative explantation were the 1-piece silicone plate-haptic large-hole design, and 29 (34.1%) were the 3-piece silicone polyimide-haptic design. The most frequent reason for explantation of both designs was optic damage, 37.3% in the large-hole design and 55.2% in the polyimide design. Optic damage did not occur in rigid PMMA IOLs. CONCLUSION: Some foldable IOL designs have a higher risk of damage during surgical insertion than rigid designs. Two modern foldable IOLs, the silicone plate-haptic large-hole and the silicone polyimide-haptic, appear to be more prone to damage during folding, loading, and implantation than other IOLs.

Device Removal↗
PubMed2002

Evaluation of 3 modern single-piece foldable intraocular lenses: clinicopathological study of posterior capsule opacification in a rabbit model.

PURPOSE: To assess the development of posterior capsule opacification (PCO) with 3 modern single-piece foldable intraocular lenses (IOLs) in a histopathological study and to compare the potential preventive effects of the IOL design and biomaterial in retarding PCO. SETTING: Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA. METHODS: Thirty-one rabbit eyes were randomly operated on with phacoemulsification and implantation of 3 single-piece foldable lenses: a hydrophilic acrylic design, the Rayner Centerflex 570H (n = 11); a hydrophobic acrylic design, the Alcon AcrySof SA30AL (n = 10); and a silicone large-hole plate design, the Staar AA-4203VF (n = 10). Central PCO (CPCO), peripheral PCO (PPCO), and Soemmering's ring formation were evaluated 3 weeks after surgery using the Miyake-Apple posterior photographic technique. Histological sections of each globe were prepared to document capsular bag status and performance of IOL geometry. RESULTS: The acrylic IOLs (Centerflex and AcrySof) had lower CPCO and PPCO scores than the silicone plate IOL (P <.05). There was no significant difference in Soemmering's ring formation among the 3 models. Pathological evaluations revealed effective blockage of migrating lens epithelial cells (LECs) at the site of the truncated optic edge of the Centerflex and AcrySof IOLs, even in the presence of large amounts of retained/regenerative cortical material. CONCLUSIONS: The AcrySof IOL has a hydrophobic surface and the Centerflex a hydrophilic surface, but no correlation to these characteristics could be identified. The single-piece AcrySof optic geometry created a clear-cut barrier effect equal to that of its 3-piece predecessor. The anatomic profile of the Centerflex IOL shows the same characteristics. The optics of both acrylic lenses have square truncated edges that functionally block ingrowth of migrating LECs toward the central visual axis, leaving clear posterior capsules. The square optic edge was an appropriate geometric configuration to create a barrier effect. There was no effect of the biomaterial on PCO prevention.

Acrylic Resins↗
PubMed2002

Interface fungal infection after laser in situ keratomileusis presenting as diffuse lamellar keratitis. A clinicopathological report.

PURPOSE: To report clinicopathological analyses of 3 cases of interface fungal infection following laser in situ keratomileusis (LASIK) and diffuse lamellar keratitis (DLK). SETTING: Center for Research on Ocular Therapeutics and Biodevices and Arthur and Holly Magill Research Center for Vision Correction, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA. METHODS: Clinicopathological analysis of 5 eyes of 3 patients who developed culture-proven interface fungal infection after LASIK was performed. Detailed pathological analysis of the amputated flap from 1 case included light, scanning, and transmission electron microscopy. RESULTS: Culture and pathological analysis revealed Candida albicans in all 3 cases. Common links among the cases were early onset of DLK following intensive corticosteroid and antibiotic treatment and later onset of interface fungal infection. All cases resolved, and good visual acuity was restored after medical treatment with antifungal agents. CONCLUSIONS: Interface fungal infection after LASIK can be sight-threatening. Early lifting of the flap, fungal culture, and aggressive antifungal treatment are required to treat this complication and avoid deleterious sequelae.

Antifungal Agents↗
PubMed2002

Loop memory of haptic materials in posterior chamber intraocular lenses.

PURPOSE: To compare the shape recovery ratios after compression of haptic materials used in the manufacture of intraocular lenses (IOLs). SETTING: Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA. METHODS: The loop memory of 40 silicone-optic posterior chamber IOLs was studied. All the IOLs had modified-C haptics made of poly(methyl methacrylate) (PMMA; n = 10), polyimide (n = 10), polyvinylidene fluoride (PVDF; n = 10), and polypropylene (PP; n = 10). After the overall diameter of each lens was measured (day 0), the lenses were inserted into plastic wells (9.5 mm in diameter) and immersed in water (37 degrees C) for 1 month. They were then placed on an open plate and allowed to reexpand for 2 months. Overall diameter measurements were performed within 5 minutes of the IOLs' removal from the wells and at subsequent time points (days 14, 28, 30, 60, 74, 88, and 95). RESULTS: The loop memory of each lens was expressed as the difference between the initial overall diameter measurement (pretest) and the measurement at each time point; the lower the value, the higher the memory. The overall difference among the 4 groups was statistically significant at each time point (P < or = .001). From days 30 to 95, silicone-PMMA, silicone-elastimide, and silicone-PVDF IOLs had similar loop memory mean values, which were significantly lower than the mean value of silicone-PP IOLs (P <.05). The latter design tended to be deformed after removal from the wells, with increased optic-haptic angulation. CONCLUSION: Studying the loop memory of haptic materials (PMMA, polyimide, PVDF, and PP) used in the manufacture of posterior chamber IOLs can help surgeons choose an appropriate IOL for each patient.

Lenses, Intraocular↗
PubMedDate not supplied

Current concepts of ocular manifestations in Marfan syndrome.

Marfan syndrome is a widespread disorder of connective tissue. It is characterized by systemic and ocular features due to mutations in the fibrillin gene. Awareness and prompt recognition of the ocular complications of Marfan syndrome may enable improvement and preservation of sight. Studies have been performed in the last few years that enable a better understanding of the genetics of the syndrome, earlier diagnosis, and improvement in the surgical techniques and options.

Eye Diseases↗
PubMedDate not supplied

Aqueous infiltration into an implantable miniaturized telescope.

The implantable miniaturized telescope (IMT) is the first intraocular magnifying system proposed for optical correction in patients with age-related macular degeneration (ARMD). The optical component is embedded in a carrying device designed as an intraocular lens that is implanted after cataract surgery. In this study, we report findings on an IMT that was explanted because of aqueous infiltration into its optic and describe the configuration of this device and the surgical technique required for its implantation. The patient, a 75-year-old male with bilateral cataract and nonexudative ARMD, underwent phacoemulsification with implantation of an IMT in the right eye. The rigid device, weighing 46.1 mg in aqueous, has an overall diameter of 13.5 mm and requires implantation through a large limbal incision. It is fixated at the 6 to 12 o'clock meridian. Follow-up examination revealed the presence of numerous droplets inside the IMT optic. The device was explanted and sent to our center for evaluation. A large fissure was found on the carrying device. However, it was unlikely the site for aqueous infiltration. Microdefects at the level of the sealing of the optical cylinder appeared to provide the opening for the inflow of aqueous that formed droplets. Based on the findings of this report the manufacturer has modified the sealing technique to avoid this complication. Current clinical trials are now ongoing to assess the efficacy of this device in providing visual rehabilitation for ARMD patients.

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