Biomedical subjects
Publications and source records attributed to L F Rich.
A 1-month-old infant with Peters anomaly had recurrent episodes of unresponsiveness, hypotension, hypotonia, hypothermia, and bradycardia. An extensive medical evaluation determined these episodes to be caused by brimonidine, an anti-glaucoma agent. There is the potential for serious toxic effects from the systemic absorption of topically applied ophthalmic agents in children.
PURPOSE: To characterize the nature and duration of contact lens training in ophthalmology residency training programs and to ascertain the comfort level of residents in fitting various types of contact lenses and in dealing with common contact lens-related complications. METHODS: Surveys were mailed to 126 ophthalmology residency program directors/coordinators and requested to be distributed to 1,381 ophthalmology residents. The questionnaire addressed issues related to contact lens training, hours of clinical and didactic training, comfort with fitting a variety of different types of contact lenses and dealing with common contact lens-related complications, and plans for incorporation of contact lens dispensing into future practice. RESULTS: Two hundred and forty-nine residents (18%) responded from 84 programs (67%). Most programs (87%) have some form of supervised contact lens training, frequently conducted by an optometrist (61% of programs), that consists of 20 hours or less of clinical experience and 20 hours or less of didactic training. A majority of the responding graduating residents (66%) feel comfortable fitting spherical soft contact lenses, while less than half of all residents feel comfortable fitting any other type of contact lens. In addition, most residents (65%) feel comfortable diagnosing and treating common contact lens-related complications. CONCLUSIONS: Most ophthalmology residency programs offer some form of supervised contact lens training which allows a majority of residents to feel comfortable fitting only spherical soft contact lenses, while also dealing comfortably with most contact lens-related problems. A comparison with previous data suggests increasing comfort with fitting most types of contact lenses over the last decade.
Numerous etiologies have been suspected to lead to sterile interface keratitis after laser in situ keratomileusis. This tan interface haze with a rippled appearance has been called Sands of the Sahara. We present 2 cases in which red blood cells entered the interface after a small hemorrhage from peripheral corneal vascularization during the microkeratome pass. Although this bleeding was controlled and all visible blood cells were removed at surgery, both patients developed the appearance of a focal interface keratitis on the first postoperative day.
PURPOSE: To describe a case in which an eye donor had prior bilateral photorefractive keratectomies and to elucidate possible methods of evaluation and screening of donor tissue. METHODS: Case report. A 62-year-old eye donor was reported to have received radial keratotomy before his death. Further investigation by the eye bank showed a history of photorefractive keratectomy (PRK), not radial keratotomy. The corneas were therefore not used for transplantation, and the eyes were evaluated by slit-lamp examination, photography, corneal topography, and histology. RESULTS: Slit-lamp and photographic examination did not indicate the presence of PRK ablations. Corneal topography mapping with the TMS-1 was relatively ambiguous for identifying PRK flattening, while multiple data formatting of the cornea with the Orbscan resulted in the strongest suggestion of prior PRK. Histologic analysis showed central corneal thinning and loss of Bowman's membrane consistent with PRK. CONCLUSIONS: In the absence of a positive donor history for PRK, current methods of screening donor tissue for prior PRK often are insufficient to exclude these corneas from use in transplantation. More refined placido imagery corneal topography or newer technologies such as the Orbscan may allow more sensitive and specific methods of donor tissue screening.
PURPOSE: To investigate whether applications of current technology, such as cryolathe and excimer laser, might improve outcomes and increase use of lamellar keratoplasty. METHODS: Six studies were performed, beginning with animals and progressing to human subjects. The first study compared cryolathed with hand-dissected rabbit corneas to ascertain which created a smoother donor interface. The second animal pilot study was done to determine whether thickness of donor cornea resection could be accurately predicted with the cryolathe. A prospective animal trial was then undertaken to compare lamellar keratoplasty outcomes using cryolathed versus hand-dissected tissue. The fourth work extrapolated previous animal findings to lamellar keratoplasty in human disease. Finally, two ongoing studies are described. The first explores the possibility of sutureless lamellar keratoplasty. The second utilizes the excimer laser to dissect the recipient stromal bed. RESULTS: The initial animal pilot study demonstrated a clearer stromal surface in cryolathed versus hand-dissected corneal tissue. The second pilot showed that plano-powered donor tissue could be generated to predetermined thickness. The prospective animal trial revealed that clear grafts of intended thickness could be obtained with cryolathing. Human studies suggested that lamellar keratoplasty using cryolathe-prepared donor tissue may offer superior results to free-hand dissection. Finally, one ongoing study indicates that sutureless lamellar keratoplasty is untenable, and the other shows that clear grafts can be obtained by combining cryolathed donor tissue with recipient photoablation. CONCLUSION: This body of work demonstrates that use of new lamellar keratoplasty technology may offer expanded scope and better outcomes than traditional lamellar keratoplasty techniques.
Cytokines such as the interleukins (IL) and tumor necrosis factor alpha (TNF alpha) have traditionally been associated with paracrine regulation of immune reactions. These proteins also have properties suggestive of functional roles in the inflammatory and reparative responses to tissue injury. In this study, mRNA levels for IL-1 alpha, IL-1 beta, IL-6, TNF alpha, interferon gamma, transforming growth factor beta 1, and CD4 were monitored in rat corneas at times from 1 hour through 2 weeks after incisional trauma or alkali burns. Transcripts for IL-1 alpha, TNF alpha, and TGF beta 1 were present in most corneal samples; whereas those for IFN gamma and CD4 were not detected. As early as 1 hour following either of these non-immunologic forms of injury, expression of IL-6 mRNA levels was induced. Only in corneas with alkali burns did IL-6 induction persist from days 1 through 7. The alkali-injured corneas also had markedly increased IL-1 beta mRNA levels from days 1 through 7. These observations indicate that cytokine mRNA is induced in the cornea by trauma without an apparent immunologic stimulus. Our data are consistent with the hypothesis that corneal tissues respond to different types of injury with different patterns of cytokine gene expression.
Using standardized freeze wounds in cat corneas, we tested the efficacy of basic Fibroblast Growth Factor (bFGF) solubilized in phosphate buffered saline (PBS) to promote endothelial healing when injected intraocularly at doses ranging from 0.01 microgram to 10 micrograms. After 6 days, animals were humanely sacrificed and corneal tissues were fixed and stained for light microscopy and computation of remaining wound areas. A significant dose-response relationship was found between the dosages of 0.01, 0.1, and 1.0 microgram of bFGF/eye and the stimulation of more completely healed endothelium six days after transcorneal freeze wounding. Significantly larger endothelial wounds were present six days after wounding when the eyes were treated with 10 micrograms of bFGF/eye compared with controls treated with PBS only.
Using standardized freeze wounds in cat corneas, we tested the efficacy of human recombinant Epidermal Growth Factor (EGF) to promote endothelial healing when solubilized in either phosphate buffered saline (PBS), 1% methylcellulose (MC), or sodium hyaluronate (NaHA), in final intraocular doses ranging from 2 micrograms to 100 micrograms of EGF. After 6 or 7 days' healing, animals were humanely sacrificed and corneal tissues were fixed and stained for light microscopy and computation of remaining wound areas. EGF in NaHA in final intraocular doses of 2 and 10 micrograms prompted significantly more complete healing of transcorneal freeze wounds to endothelium compared with endothelium of eyes treated with NaHA control solution alone. EGF in PBS or in MC in doses ranging from 2-100 micrograms/eye did not promote more complete wound healing than that seen in eyes treated with their respective vehicle solutions alone. All vehicle solutions were associated with similar degrees of wound healing, implying that they have no intrinsic healing properties.
Several growth factors have been evaluated for their effects on corneal wound healing but few studies have yet demonstrated an acceleration of endothelial repair in vivo. Mesodermal Growth Factor (MGF) was tested in vivo by making standardized freeze wounds in cat corneas and immediately injecting one of four concentrations of MGF in sterile phosphate buffered saline (PBS), or PBS alone, into the anterior chamber. Seven days later, the animals were sacrificed and the corneas excised and stained. Descemet's membrane and endothelium were dissected and mounted onto glass slides. The wound areas were photographed, measured and compared statistically. Those cats receiving the three lowest doses of MGF had significantly smaller wounds than controls (p less than 0.05).
Vasoconstrictors such as phenylephrine and naphazoline are used in ophthalmology to decrease hyperemia associated with allergic conjunctivitis and contact lens wear. There is a suspicion, however, that chronic use of these agents can produce dry-eye symptoms in some patients. The purpose of this study was to determine whether vasoconstrictor use interferes with tear film adequacy by decreasing mucin-secreting goblet cells. Cellulose acetate filter strip impressions were taken from the bulbar conjunctiva of rabbit eyes treated with vasoconstrictors or artificial tears for varying periods of time, and the number of goblet cells per light microscopic field counted. There was no significant difference between the number of goblet cells in control and vasoconstrictor-treated animals within each time period. These results indicate that conjunctival goblet cell density is not significantly affected by topical vasoconstrictor use.
We examined the morphologic characteristics of the corneal endothelium in three groups of contact lens wearers: those who had used daily-wear soft contact lenses for an average of 6.3 years, long-term (greater than 20 years) users of hard contact lenses, and former users of hard contact lenses who had worn them for an average of 9.6 years but who had discontinued them for an average of 4.3 years. When compared to age-matched controls, all groups had similar endothelial cell densities but demonstrated significant increases in variation of cellular size (polymegethism) and shape (pleomorphism). We found that daily-wear soft contact lenses can cause endothelial polymegethism and pleomorphism similar to those caused by hard contact lenses and that the endothelial changes induced by hard contact lenses are more profound with greater duration of wear and are apparently not completely reversible.
The majority of patients with recurrent corneal erosion respond to conventional forms of therapy such as topical lubricants, patching, debridement, or bandage soft contact lenses. However, there remain a small number who do not. For the small number of patients who do not respond to this type of treatment, this report describes a procedure: multiple anterior stromal punctures are created that presumably stimulate more secure epithelial adhesion to the underlying stroma. Of 21 eyes in 18 patients treated in this manner, three eyes required retreatment of adjacent areas; otherwise, there were no recurrences in follow-up periods ranging from 5 months to 12 years. This procedure is a simple and effective method for safe office treatment of patients with recalcitrant recurrent erosion.
Morphometric analysis of the corneal endothelium was performed on 11 eyes of patients who underwent anterior radial keratotomy with the contralateral eye serving as the controls. We analyzed cell density, variation in cell size (polymegethism), and cell shape (pleomorphism) by computer analysis of central and midperipheral specular micrograms one year after surgery. The central endothelial density decreased from 2,503 to 2,419 cells/mm2 (3.3% decrease). The coefficient of variation in cell size (polymegethism) was 0.290 preoperatively and 0.309 postoperatively centrally. Central hexagonality was reduced centrally from 61.4% preoperatively to 56.8% in the operated on eye. These differences were not statistically significant (P greater than .05). In a separate subgroup of six patients, midperipheral specular microscopy under and between incisions disclosed a similar pattern of mild cell density decrease and morphometric remodeling one year after surgery. No morphometric characteristic was significantly different from the central control values (P greater than .05), suggesting that the corneal endothelial monolayer had stabilized one year after radial keratotomy.
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Keratocyte survival in corneal lenticules preparing by cryolathing was evaluated using the vital stain, nitroblue tetrazolium. A comparison was made between lenticules inserted in the recipient cornea immediately after grinding and those inserted after one week of storage in either glycerin or liquid nitrogen. In all three groups, no viable keratocytes stained in the donor lenticule at one or three days after surgery. Ten days after insertion, however, all three groups showed a few staining cells within the body of the lenticule, suggesting beginning repopulation of the donor collagenous framework with viable cells from the host. Since the donor keratocytes are dead, healing of keratophakia lenticules is not influenced adversely by storing the donor material. Thus, keratophakia lenticules could be prepared in advance of surgery and stored in glycerin or liquid nitrogen until needed.
Using cats as an experimental model, we compared the clarity of fresh, glycerine-preserved and nitrogen-preserved lenticules (corneal stromal implants) in keratophakia. No difference in final clarity was observed and the change in corneal curvature was maintained. In six patients freshly cut lenticules were used; in nine patients liquid nitrogen-preserved lenticules were used. Again, no difference in final clarity or correction was noted. The use of preserved, precut tissue in keratophakia will make this technique available to the general ophthalmic surgeon.
A technique is described for producing lamellar buttons from donor corneas using modified keratomileusis. Although refractive keratoplasty is complex, producing planopower corneal discs is much simpler. Accuracy in preparing lamellar tissue of known thickness is potentially greater with keratomileusis than free-hand dissection and should produce better visual results. Eye banks could store precut lamellar buttons in various thicknesses and thereby decrease the amount of time spent in the operating room during lamellar keratoplasty.