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Biomedical subjects

D R Hardten

Publications and source records attributed to D R Hardten.

At least 19 recordsLinked to original sources
PubMed1998

Photorefractive keratectomy for residual myopia after radial keratotomy. PRK After RK Study Group.

PURPOSE: To evaluate the visual outcomes in patients having photorefractive keratectomy (PRK) to correct residual myopia after radial keratotomy (RK). SETTING: Nine refractive surgery centers in the United States and one in South Korea. METHODS: This retrospective analysis comprised 38 eyes of 32 patients treated with PRK after RK and followed for 12 months. Analysis was based on pre-RK and pre-PRK refraction as well as response to RK (pre-RK minus pre-PRK refractions). RESULTS: Mean pre-RK and pre-PRK refractions were -8.11 diopters (D) +/- 2.92 (SD) and -4.28 +/- 2.08 D, respectively. One month after PRK, mean refraction was +0.42 +/- 1.56 D and regressed to -0.95 +/- 1.24 D at 12 months. At 12 months, 65% of eyes had an uncorrected visual acuity of 20/40 or worse, and 11.1% lost 2 or more lines of best corrected acuity. Of eyes with an original erro of -6.00 or less, 81.8% were within +/- 1.00 D of intended correction at 12 months and of those with an original error of -9.12 to -20.00 D 50.0% (P = .004). All eyes with residual (pre-PRK) errors of -3.00 D or less and 42.9% with a residual error of -6.12 to -9.00 D were within +/- 1.00 D of intended correction (P = .07). There were no statistically significant differences in the response to PRK between eyes that had an RK response of 0 to 3.00, 3.12 to 6.00, or 6.12 to 12.00 D. CONCLUSION: Patients with lower original and residual myopia achieved better visual outcomes after PRK than those with higher myopia. The amount of myopic correction achieved using RK was not predictive of the amount of myopic correction using PRK.

Adult↗
PubMed1997

Laser In Situ keratomileusis (LASIK) for the treatment of low moderate, and high myopia.

PURPOSE: To evaluate the efficacy, safety and predictability of LASIK in the treatment of low, moderate and high myopia. METHODS: A perspective study of LASIK for low myopia of -0.75 to -6.00 with less than +1 D of astigmatism and for moderate and high myopia of -6.12 to -20 D with astigmatism up to +4.50 D was performed at our institution from March through November, 1996. The Chiron automated corneal shaper was used for the initial flap, and either the Summit or VISX laser was used for the refractive ablation. Preoperative refraction, uncorrected and corrected visual acuity were compared to postoperative refraction, uncorrected and corrected visual acuity. One day and 1 month results were available on all patients. RESULTS: In the low myopia group 101 eyes underwent LASIK with a mean preoperative spherical equivalent of -4.16 +/- 1.41 D (-0.75 D to -6.00 D). Mean preoperative astigmatism was +0.4 +/- 1.29 D (0 to 0.75 D). At 1 day, 48% were 20/25 or better and 80% were 20/40 or better. The day 1 mean spherical equivalent was +0.4 +/- 0.75 D with 86% between +/- 1.00 D of emmetropia. At 1 month, 50% were 20/25 or better and 90% were 20/40 or better. The 1 month mean spherical equivalent was -0.26 +/- 0.65 D with 89% between +/- 1.00 D of emmetropia. In the high myopia group 198 eyes underwent LASIK with a preoperative mean spherical equivalent of -8.34 +/- 2.15 D)-6 to -20D) and a mean preoperative astigmatism of +1.18 +/- 0.88 D (0 to +4.5 D). At 1 day postoperatively, 17% were 20/25 or better, and 61% were 20/40 or better. The mean day one spherical equivalent was -0.26 +/- 1.56 D with 58% between +/- 1.00 D of emmetropia. At 1 month, 35% were 20/25 or better and 71% were 20/40 or better. The 1 month mean spherical equivalent was -0.28 +/- 1.18 with 63% within +/- 1.00 D of emmetropia. CONCLUSION: Early results of using LASIK to treat low, moderate and high degrees of myopia with and without astigmatism appear promising, although longer follow-up and nomogram refinement are needed.

Adult↗
PubMed1996

Corneoscleral melt after pterygium surgery using a single intraoperative application of mitomycin-C.

A 59-year-old man underwent pterygium excision with intraoperative application of 0.2 mg/ml (0.02%) mitomycin-C placed on the scleral bed for 3 min. A sliding conjunctival flap was used to cover the exposed limbus and sclera. Five weeks after the original surgery, the patient had mild trauma and noted decreased vision. At that time, it was noted that he had a corneoscleral melt with perforation. The patient was managed with a lamellar transplant in this area. Intraoperative single-dose application of topical mitomycin-C can be associated with serious complications. This case occurred despite the fact that this patient received the lowest dose used in a series of 25 eyes using the same technique without any other complications. Although topical mitomycin-C is effective as an adjunct to pterygium surgery and may reduce recurrence, the safety and efficacy of various concentrations and dosing schedules need further definition.

Chemotherapy, Adjuvant↗
PubMed1994

Results one year after using the 193-nm excimer laser for photorefractive keratectomy in mild to moderate myopia.

As part of a clinical trial, photorefractive keratectomy using the VISX 2015 193-nm excimer laser was performed on 91 healthy eyes of 91 patients. Preoperative refractive errors (spherical equivalent) ranged from -1.00 to -7.50 diopters (mean, -4.16 +/- 1.41 diopters). No patient had more than 1 diopter of refractive astigmatism. Six months postoperatively, the average residual refractive error was +0.09 +/- 0.63 diopters (range, -2.13 to +1.63 diopters). Correction within 1 diopter of that attempted was attained in 85 eyes (93%). Uncorrected visual acuity of 20/40 or better was attained in 86 eyes (95%) and was 20/25 or better in 67 eyes (74%). At one year, follow-up information was available on 85 eyes of 85 patients. The average residual refractive error was -0.15 +/- 0.65 diopters (range, -2.50 to +1.63 diopters). Correction within 1 diopter of that attempted was attained in 85 eyes (93%). Uncorrected visual acuity was 20/40 or better in 83 eyes (98%) and was 20/25 or better in 68 eyes (80%). One patient lost three lines of best-corrected visual acuity because of corneal haze, dropping from 20/15 to 20/30, whereas all other patients returned to best-corrected visual acuity within one line of their preoperative best-corrected visual acuity. Photorefractive keratectomy with the 193-nm excimer laser appears to be a useful treatment modality for the reduction of mild to moderate myopia.

Adolescent↗
PubMed1994

Linear endotheliitis.

We treated six eyes of five patients with linear endotheliitis. This entity appears clinically as a line of keratic precipitates on the corneal endothelium that progresses centrally and is accompanied by peripheral stromal and epithelial edema. All five patients had ocular pain, redness, and photophobia. One eye had an episode of a dendritic lesion typical of herpes simplex. Two eyes had a history of cataract extraction before developing linear endotheliitis. We treated all patients aggressively with a combination of corticosteroids and antiviral agents. Complete resolution of inflammation and edema occurred in all cases. Four patients required the use of oral acyclovir to control the inflammation and prevent recurrence of the disease. Linear endothelitis is a distinct form of endotheliitis that may be associated with herpes simplex virus, and treatment included corticosteroid and antiviral therapy.

Acyclovir↗
PubMed1994

193-nm excimer photorefractive keratectomy in high myopia.

PURPOSE: To evaluate the refractive results of 193-nm excimer laser photorefractive keratectomy (PRK) performed on 48 highly myopic eyes in a multicenter study. METHODS: A Visx 2015 or 2000 argon-fluoride excimer laser and a single-zone ablation technique were used. Postoperatively, eyes were treated with topical fluoromethalone for up to 5 months. Most eyes were treated with a 6.0- to 6.2-mm beam diameter after undercorrections and increased regression were noted with a 5.5-mm beam in earlier studies. Forty-eight eyes were treated for myopia, which was between -8.0 and -15.25 diopters (D) (spherical equivalent). The mean preoperative refraction was -11.2 D. Retreatment was performed after 6 to 16 months on 11 eyes for undercorrection. All eyes not retreated were followed for at least 12 months. RESULTS: At 6 months, follow-up was available on 47 eyes. Of these eyes, 40% and 64% achieved corrections within 1 and 2 D of attempted correction, respectively. At 1 year, 60% of eyes attained 20/40 visual acuity or better uncorrected. Eleven patients (23%) were retreated between 6 to 16 months for undercorrection and/or regression. After retreatment, 47% and 81% of eyes achieved corrections within 1 and 2 D of attempted correction, respectively. At 1 year, 15% of eyes lost two lines of best-corrected visual acuity, and no eyes lost more than two lines. There was slightly more corneal haze seen in this group compared with the haze seen in patients undergoing PRK for low and moderate myopia. CONCLUSIONS: These data show that excimer PRK can correct high amounts of myopia with reasonable stability after 6 months. Excimer PRK is an effective surgical treatment of severe myopia, but long-term follow-up is still needed to assess the stability of its effect.

Adult↗
PubMed1994

Treatment of low, moderate, and high myopia with the 193-nm excimer laser.

PATIENTS AND METHODS: Photorefractive keratectomy using the VISX 2015 193-nm excimer laser was performed on 134 consecutive eyes of 97 myopic patients by the two authors. Preoperative refractive errors (spherical equivalent) ranged from -1.63 to -14.25 diopters (D) (mean, -5.76 +/- 2.40 D). Follow-up of 6 months was available on 110 eyes. At six months, the average residual refractive error was +0.16 +/- 1.13 D (range -2.88 to +3.38). Correction within 1 D of that attempted was obtained in 77 eyes (70%). Uncorrected visual acuity of 20/40 or better was achieved in 89 eyes (81%), and 20/25 or better in 54 eyes (49%). RESULTS: At one year, follow up was available on 57 eyes. The average residual refractive error was -0.22 +/- 0.87 D (range -3.00 to +2.00 D). Correction within 1 D was achieved in 47 eyes (82%). Visual acuity was 20/40 or better uncorrected in 50 eyes (88%), and 20/25 or better in 35 eyes (61%). One patient lost three lines of best corrected visual acuity and 4 patients lost 2 lines of best corrected visual acuity from corneal haze or irregular astigmatism, while all other patients returned to best corrected visual acuity within one line of their preoperative best corrected visual acuity. CONCLUSION: Photorefractive keratectomy with the 193-nm excimer laser appears to be a useful treatment modality for the reduction of low to moderate myopia.

Adult↗
PubMed1994

In vitro evaluation of the effects of metronidazole on rabbit corneal epithelial cells.

Because of its usefulness in treating facial rosacea, metronidazole may also be an effective treatment for ocular rosacea. The toxicity of metronidazole on the corneal epithelium has not previously been reported. In this study, the effects of metronidazole on rabbit corneal epithelium in vitro were evaluated. Epithelial cell cultures were exposed to various concentrations of metronidazole to determine its effect on cell morphology, viability, and wound healing. Both morphological changes and cell loss were seen after 1 day of incubation in media containing metronidazole at concentrations of > or = 3.0 mg/ml. In media with metronidazole at 1.0 mg/ml, these toxic effects were not seen. The effects of metronidazole on wound healing were determined by comparing the area of wounds in the epithelial cell layer for time periods of up to 44 h. There was no statistically significant delay in wound closure when cells were incubated in media containing metronidazole at a concentration of 2.0 mg/ml as compared with cultures incubated in media without metronidazole. However, a significant delay in wound closure occurred at concentrations of > or = 3.0 mg/ml. The results at these drug concentrations suggest that metronidazole has low corneal epithelial toxicity. Allowing for the dilutional effects of tears in patients with normal tear function, concentrations of 4.0-5.0 mg/ml (0.4-0.5%) would probably be tolerated by the corneal epithelium. Clinical safety and efficacy studies are necessary to determine if topical metronidazole will prove useful for the treatment of ocular rosacea.

Animals↗
PubMed1994

Effect of topically administered platelet-derived growth factor on corneal wound strength.

Since the cornea is an avascular tissue, the wound healing process is lengthy, with a need for sutures to stabilize the wound for a long time. Platelet-derived growth factor (PDGF) has been shown to accelerate wound healing in rat dermal models. Accelerated healing, if unaccompanied by side effects may reduce suture related complications such as astigmatism and infectious keratitis. This study evaluated the effect of PDGF on wound strength in corneal laceration and penetrating keratoplasty models using New Zealand white albino rabbits. Twenty-two rabbits were used in the corneal laceration model and sixteen rabbits in the penetrating keratoplasty model. The treated rabbits received 385 picomoles/drop of PDGF-BB dissolved in balanced salt solution six times on day 1 and three times a day for the remainder of the study. The control rabbits received balanced salt solution in the same dosing schedule. The pressure required to rupture the wound was measured using a pressure transducer. In the laceration model the PDGF treated group had mean (+/- standard deviation) average pressures on day 7 of 360 +/- 102 mm Hg for wound rupture compared to 210 +/- 102 mm Hg in the control group. (p = 0.005). The average pressures in the penetrating keratoplasty model on day 17 were 707 +/- 201 mm Hg for the controls and 1042 +/- 292 mm Hg for the PDGF treated group (p = 0.026). Histopathological evaluation of eyes not subjected to bursting showed increased fibroblasts at the wound junction with an increase in types III and type IV collagen production.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Topical↗
PubMed1993

Clinical findings in Brown-McLean syndrome.

The Brown-McLean syndrome is a clinical condition with corneal edema involving the peripheral 2 to 3 mm of the cornea. The edema typically starts inferiorly and progresses circumferentially, but spares the central portion of the cornea. Additionally, the edema is associated with a punctate orange-brown pigmentation on the endothelium underlying the edematous areas. Central cornea guttata is frequently seen. This condition occurs most frequently after intracapsular cataract extraction, but may also occur after extracapsular cataract extraction and phacoemulsification, or pars plana lensectomy and vitrectomy. Surgical complications and multiple intraocular procedures are frequently observed in these patients. Less frequently, the Brown-McLean syndrome can occur in eyes that have not had surgery. We studied the clinical characteristics of 43 affected eyes of 32 patients. New findings included Brown-McLean syndrome occurring in two eyes of a phakic patient with intermittent angle-closure glaucoma. Two eyes developed Brown-McLean syndrome after phacoemulsification and one eye developed peripheral edema after pars plana vitrectomy and lensectomy. Additionally, severe, infectious keratitis occurred after rupture of peripheral bullae in two eyes. Patients with this condition should be examined periodically and educated regarding the early clinical signs of corneal ulceration.

Adult↗
PubMed1993

Clinical and anatomical study of the effect of transscleral fixation of posterior chamber lenses on early postkeratoplasty astigmatism.

We reviewed the pattern of astigmatism after penetrating keratoplasty and transsclerally sutured posterior chamber lens (TSPCL) placement in 73 patients. Thirty-five patients (48%) had an axis of astigmatism oriented perpendicularly to the haptics of the TSPCL. Twenty-seven patients (37%) had an orientation of astigmatism that was in the same meridian of the haptics of the TSPCL. Eleven patients (15%) had an axis of astigmatism oriented obliquely to the meridian of the haptics of the TSPCL. The distance the haptic fixation sutures were placed behind the limbus appeared to be correlated with the orientation of astigmatism. Patients having the lens fixated within 0.75 mm of the limbus were more likely to have astigmatism oriented perpendicular to the meridian of the haptics of the posterior chamber lens in the early postoperative period. Patients having the lens fixated 2-3 mm posterior to the limbus were more likely to have astigmatism oriented in the same meridian as the haptics of the posterior chamber lens in the early postoperative period. In an eye bank model of TSPCLs during penetrating keratoplasty, the placement of a posterior chamber lens with haptics fixated within 0.75 mm of the limbus significantly widens the recipient bed an average of 0.3 mm in the meridian of the haptics of lens placement (p = 0.02). When the posterior chamber lens haptics were fixated 3 mm posterior to the limbus, the recipient bed was significantly narrowed in the meridian of lens placement an average of 0.2 mm (p = 0.02). It appears that the TSPCLs may have an effect on early postkeratoplasty astigmatism by distorting the corneal wound at the time of keratoplasty.

Aged↗
PubMed1993

Transscleral neodymium:YAG cyclophotocoagulation: comparison of 180-degree and 360-degree initial treatments.

In order to help clarify how much Neodymium:YAG transscleral cyclophotocoagulation (Nd:YAG CPC) treatment should be given to maximize effectiveness and minimize complications in the treatment of refractory glaucomas, we retrospectively reviewed and compared the results achieved with an initial 180-degree noncontact Nd:YAG CPC treatment with those achieved with an initial 360-degree treatment. Forty-five patients were in the 180-degree group and 21 in the 360-degree group. Mean follow up after the first Nd:YAG CPC treatment was 10.2 +/- 7.5 months. The average pretreatment intraocular pressure (IOP) in the 180-degree group was 33.5 mm Hg. After one treatment, IOP in these patients dropped an average of 8.4 mm Hg and was controlled successfully (5 to 22 mm Hg) in 14 (31%). After a mean of 2.0 treatments, IOP in these patients dropped an average of 15.3 mm Hg, and successful IOP control was ultimately achieved in 35 (78%). The average pretreatment IOP in the 360-degree group was 41.8 mm Hg. After one treatment, IOP in these patients dropped an average of 19.4 mm Hg and was controlled successfully in 11 (52%). After a mean of 1.3 treatments, IOP in these patients dropped an average of 20.7 mm Hg, and successful IOP control was ultimately achieved in 13 (62%). Our study suggests that repeated 180-degree treatments can be successful. However, because we found that IOP was controlled more rapidly with fewer major complications in the 360-degree group, the risk-to-benefit ratio may be better for initial 360-degree treatment.

Aged↗
PubMed1992

Excimer laser photorefractive keratectomy in high myopia. A multicenter study.

Excimer photorefractive keratectomy was performed at three centers on 16 highly myopic eyes (8 diopters [D] or more) and followed up for 6 months. Ablation depths ranged from 137 to 230 microns. The preoperative spherical equivalent of myopia ranged from -8.62 D to -14.50 D (mean +/- SD, -11.57 +/- 1.62 D). Six months after surgery, the mean refraction (spherical equivalent) was -0.90 +/- 2.13 D. Eleven of 16 eyes achieved refractions within 2 D of that attempted. All eight patients at one site were treated with a maximum-beam diameter of 6.0 mm and were corrected to within 2 D of that attempted, and all were 20/40 or better uncorrected. Three of eight eyes at the other two sites were treated with a 5.5- or 5.6-mm maximum-beam diameter, which achieved corrections within 2 D of that attempted. The epithelium healed within 3 to 4 days, and there were no erosions. Mild subepithelial reticular haze, similar to that seen with excimer photorefractive keratectomy for lower myopia, was seen in all patients, with two patients experiencing more significant corneal haze. This peaked at 3 to 6 weeks and then gradually diminished. All but two patients had a return of their best corrected preoperative visual acuity to within one Snellen line at 6 months. This preliminary study shows excimer photorefractive keratectomy to be a promising surgical treatment for patients with higher myopia.

Adult↗
PubMed1992

Persistent superficial punctate keratitis after resolution of chlamydial follicular conjunctivitis.

Two cases of follicular conjunctivitis due to Chlamydia trachomatis followed by punctate epithelial keratitis are described. Both cases were initially treated with either oral tetracycline or doxycycline with resolution of the follicles. These two patients subsequently had recurrent, bilateral grayish lesions at various levels in the corneal epithelium that stained in a punctate fashion with fluorescein. There was anterior stromal edema associated with some of these lesions in one case. The lesions were confined mostly to the central cornea. These recurrent lesions were unassociated with a conjunctival reaction, were unresponsive to oral tetracycline, but were exquisitely responsive to low doses of topical steroids. Chlamydial conjunctivitis and the associated keratitis typically shows no response or actual exacerbation of symptoms with topical steroids, and the keratitis shows a predilection for the upper half of the cornea. These patients demonstrate that chlamydial keratoconjunctivitis might result in a clinical appearance consistent with Thygeson's superficial punctate keratitis.

Adolescent↗