Two Cases of Corneal Ring Infiltrates from Topical Anesthetic Abuse

PURPOSE: Topical anesthetic abuse resulting in sight-threatening keratitis may be seen as a masquerade syndrome in many cases because of ring infiltration of the cornea. The authors report two cases of keratopathy from topical anesthetic abuse that were originally suspected as infectious keratitis because of ring infiltration of the cornea METHODS: The medical records of two patients were retrospectively reviewed. The pathogenesis, diagnosis, and treatment of ring infiltrates were evaluated. RESULTS: The two patients presented a nonhealing epithelial defect, marked stromal edema, folds in Descemet's membrane, and typical stromal ring infiltrates of unknown etiology. The patients initially were treated empirically with antibacterial and antifungal agents in suspicion of infectious keratitis. These patients had sustained severe ocular pain, and chronically used topical anesthetics (0.5% proparacaine hydrochloride in one patient and 0.4% benoxinate hydrochloride in the other) for several weeks. All microbiology work-ups for the identification of infectious organisms including acanthamoeba were negative. After topical anesthetic was discontinued in two patients, amniotic membrane transplantation was performed on one patient. Corneas in two patients were re-epithelialized with mild scarring with topical antibiotic and steroid treatment.

Correlation of sFas Level with Uveitis Severity

PURPOSE: The aim of this study is to determine the soluble Fas (sFas) levels in both sera and aqueous humor in patients with uveitis and compare them to the uveitis severity. METHODS: We measured the sFas levels in both sera and aqueous humor (AH) of patients (n=40) with uveitis and non-uveitis controls (n=27). The patients with uveitis comprised 24 Behcet's disease, 6 panuveitis, 5 anterior uveitis, 2 lens induced uveitis, 1 Vogt-Koyanagi-Harada-disease, 1 sarcoidosis, and 1 retinal vasculitis. The severity of uveitis was determined by the Hogan's grading method (0~4 grade) at the time of sampling. RESULTS:The concentration of aqueous sFas in uveitis patients was significantly higher than that in nonuveitis controls, while there was no difference in the serum concentration of sFas between the two groups. In the paired samples of serum and AH, obtained simultaneously, the aqueous sFas levels were higher than serum Fas levels in patients with uveitis, whereas the non-uveitis controls displayed significantly lower sFas levels in AH than in the serum. The sFas levels in AH or serum were not different between Behcet's uveitis and non-Behcet's uveitis. However, in patients with Behcet's uveitis, circulating sFas strongly correlated with aqueous sFas, which was not so in those with non-Behcet's uveitis. Patients (n=29) with more active (grade> or =2) uveitis had significantly higher levels of aqueous sFas than those (n=11) with less active (grade<2) uveitis. After treatment with steroid and/or immunosuppressive agents, aqueous sFas levels were decreased in parallel with a reduction in the number of inflammatory cells in the anterior chamber. CONCLUSIONS: The levels of sFas were elevated in patients with uveitis and correlated well with uveitis severity.

Ocular Penetration of Topical Ofloxacin in Rabbit Eye with Amniotic Membrane Transplantation

PURPOSE: We evaluated ocular penetration and drug level in tear after topical ofloxacin instillation in rabbit eye with amniotic membrane transplantation(AMT). METHODS: In the first set of experiment, 24 rabbits(24 eyes) were divided into 4 groups according to the epithelial removal or AMT. Topical ofloxacin was instilled 4 times every 15 minutes and then, 1 hour after the last eyedrop, the samples of amniotic membrane(AM), cornea and aqueous humor were collected. In the second set of experiment, 24 rabbits(24 eyes) were divided into 6 groups according to the freshness of AM or its attached time. Topical ofloxacin was applied to eyes and then, tear samples were collected at 30 minutes, 1, 2, 4, and 6 hours. Ofloxacin concentration in the samples of two experiments were evaluated using high performance liquid chromatography. RESULTS: Mean ofloxacin concentrations in cornea and aqueous humor were statistically higher in deepithelized corneas regardless of AMT(P<0.05). And mean tear levels of ofloxacin in AMT groups were statistically higher than those in non-AMT groups(P<0.05). CONCLUSIONS: AMT seems to interfere with the ocular penetration of topical ofloxacin in normal rabbit cornea, but rather enhances ofloxacin penetration in the cornea with epithelial defect. And also the ofloxacin level in tear was higher in eyes with AMT up to 1 hour after topical ofloxacin use. Therefore it seems that AM has potential to act as an effective drug delivery system.

Efficacy of Polymerase Chain Reaction in Early Diagnosis of Herpes Simplex Keratitis in Rabbit Model

We evaluated the efficacy of polymerase chain reaction(PCR)in early diagnosis of herpes simplex keratitis(HSK)in rabbit model and compared the sensitivity and specificity of PCR in two kinds of primers. Only one eye of 8 rabbits was inoculated with HSV Type 1(F strain, ATCC VR-73)to induce HSK, and the other eye was used as control. Rabbit cornea was examined under slit lamp examination and PCR test of tear and corneal scraping specimens were performed at 1, 3, 5, 7, and 10th post-inoculation day. The sensitivity of PCR with POL primer was 100%in tear and corneal scraping specimens. The sensitivity of PCR with POL primer and LAT primer were 80%and 100%respectively. PCR test is very useful diagnotic tool for the early diagnosis of HSK in rabbit model. In addition, PCR test with corneal scraping specimens provided better yield compared with tears.

20% Alcohol Toxicity on Rabbit Corneal Epithelial Cells: Electron microscopic study

PURPOSE: To evaluate 20% ethanol toxicity on the rabbit corneal epithelium, ethanol-treated rabbit corneas were examined with electron microscopy. METHODS: Rabbit corneas(24 eyes) were treated with 20% ethanol for 30 seconds, 1 minute, and 2 minutes by using LASEK(Laser Assisted Subepithelial Keratomileusis) instruments, and washed with sterile water. Zero time, 1, 3, 5 days after ethanol treatment, corneas were excised and examined with scanning and transmission electron microscopy. RESULTS: Widespread damage or disappearance of microvilli and local breaks of intercellular junction were observed. The changes were more severe in corneas with longer ethanol treament. In corneas with over 1 minute ethanol treatment, slough of superficial corneal epithelium was shown and increased with time. It was difficult to recognize microvilli or distinctive intercellular junction in corneas with 2 minute-treament. These pathologic changes persisted 5 days after ethanol-treatment. CONCLUSIONS: From these results, 30 seconds to 1 minute-ethanol treatment is recommended in corneal surgery to avoid severe, persisting damage of superficial corneal epithelium.

Accuracy of Intraocular Lens Power in Cataract Patients Underwent Excimer Laser PRK

We retrospectively evaluated postoperative refraction of four patients(five eyes)who received intraocular lens implantation after excimer laser photorefractive keratectomy (PRK).The mean age of the patients was 44.8 years and 3 patients were female and 1 patient was male.The mean interval between PRK and cataract operation was 20.2 months (1 to 45 months)and the mean follow-up time after cataract operation was 16.2 months(2~43months).Phacoemulsification and PMMA-PCL(6.0~6.5 mm)implantation were made in all cases.SRK-II formula,the most popular empirical formula was used in first 3 cases(group I),but Idem-lens formula,a primitive theoretical formula was used in another 2 cases (group II)after occurrence postoperative refraction errors in group I .In group I and II,the mean postoperative refraction error was +3.00 diopters and +0.50 diopters and uncorrected visual acuity at postoperative 2 months was 20/60 and 20/24 respectively.The mean of calculated IOL-power was -3.75 diopter in group I and -0.625 diopter in group II.From these results,the empirical formula is definitely unsuitable for the calculation of IOL power in the cataract operation following excimer laser PRK. Moreover,although a primitive one,Idem-lens theory could be temporally useful for the IOL-power calculation in such cases.In conclusion,new formula is required for the cataract operation following excimer laser PRK.

Effect of Epidermal Growth Factor on the Wound Healing after Excimer Laser Photokeratectomy in Rabbits

Epidermal growth factor (EGF) has been believed to promote the corneal epithelial wound healing by stimulating the proliferation of the epithelial cells located at the wound base and limbus. Thus we made transepithelial photokeratectomy by excimer laser to cornpare the rate of corneal wound healing and the histological findings between a group received only photokeratectomy (control) and a group with photokeratectorny and topical EGF treatment. The results showed that the corneal epithelial wounds treated with EGF after excimer laser photokeratectomy was closed significantly faster than those without. EGF, PCNA immunoreactive cells appeared at. the basal cell layer of limbus and wound area in EGF-treated groups but, not, in control group These resuite suggest that EGF accelerates the corneal epithelial wound healing after excimer laser photokeratectomy by stimulating the proliferation of the basal cells of limbus and wound area and results in 8 faster wound healing time.

Comparison of Color and Contrast Sensitivities Between UVCY(Non-Cyanoptic) and Conventional UV-AB IOLs

The non-cyanoptic, yellow colored posterior chamber intraocular lens (UVCY-IOL, HOYA, Japan) was specially designed to reduce the penetration of ultraviolet (UV) and short wave length visible light(400-500 nm) by adding yellow coloring dye(monomethin) for the pervention of aphakic or pseudophakic cyanopsia, and the obtaining closer color sensitivity and contrast sensitivity to the normal phakic eyes. In this study, we implanted both yellow colored IOLs in 16 eyes and conventional clear UV absorbing IOLs in 12 eyes. They were prospectively followed up for 6 months with questionairs asking subjective symptoms and with contrast s~nsitivity test in order to evaluate the color sensitivity and contrast sensitivity. The subjective symptoms of cyanopsia, photophobia, and glare were signi ficantly reduced in the UVCY-IOL group comparing to the conventional UVAB-IOL group. But in few cases of UVCY-IOL implantation(18.8%) were in episode transiently on xanthopsia with some dim state in early postop periods. The contrast sensitivity pattern of UVCY-IOL group was very similar to that of normal phakic group. The decrement of contrast sensitivity was less in UVCY-IOL group than in conventional UVAB-PCL group. The amount of decreased contrast sensitivity of UVCY-IOL group in scotopic condition was similar to that of conventional UVAB-IOL group. The result of this study suggests that yellow colored IOL is effective in decre asing cyanopsia and photophobia and in improving contrast sensitivity after cataract surgery especially in the early postoperative period. And also we recommend patients would receive UVCY-IOL implantations in both eyes if you have cataract on both eyes.

Mechanical Analysis of the Excimer Laser Photorefractive Keratectomy

This study proposed a mechanical model of the excimer laser photorefractive keratectomy(PRK) for myopia patients utilizing finite element method, which is a simulation technique widely used in engineering fields. The outcomes of the surgery depends on many factors, which are also dependent on each other. In this study, some mechanical factors are selected and the effects of the selected factors on the surgical results were analyzed. One of the important factors in the finite element analysis is the mechanical properties of the object. The representative characteristic of the human cornea is that it shows highly nonlinear property in the stress-strain relationship like most soft tissues in the human body. Therefore, the nonliear property was adopted in this study. Other important mechanical properties which affect the outcomes of the surgery are: a preoperative thickness, intraocular pressure, diameter of ablation zone and the depth of ablation. With various changes of the those mechanical factors, the outcomes of the surgery were predicted using the finite element method. The results show the qualitative agreement with clinical outcomes also promising agreement quantitatively. Therefore, this study shows a potential of the finite element method in clinical application of excimer laser PRK.

Clinical Results of Photorefractive Keratectomy for Undercorrected Myopia after Radial Keratotomy

We report clinical results of 13 myopic patients(18 eyes), which remained undercorrected following radial keratotomy and then underwent photo refractive keratectomy(PRK) with an excimer laser(193 nm) to correct the residual myopia, with follow up of 1 year. Patient's mean age was 26 years. The time interval between radial keratotomy and PRK ranged 12 to 98 months(mean 40 months); group I(14 eyes) 6 diopter. At one year after PRK, uncorrected visual acuity was 20/25 or more in 15 eyes(83%). Mean manifest refractive error changed from -3.41 +/- 1.97D preoperatively to -0.91 +/- 0.41D after PRK in group I and fron -7.44 +/- 0.61D to -1.88 +/- 0.97 in group II. The mean keratometric power changed from 40.38D preoperatively to 38.32D after PRK in group I and from 42.93D to 38.56D in group II. Most common complaints were halo phenomenon and decreased vision at night. Persistent comeal haze(grade 2) was noted only in one eye at 3 months after PRK, but reduced to trace at 1 year. No other significant complications occurred. Therefore, excimer laser PRK appears to be an available method to correct residual myopia after radial keratotomy.

The Measurement of the Laser Space in the Planned Extracapsular Cataract Extraction with the PCL

Cataract extraction is one of the most successful surgical operations currently being performed. In particular, extracapsular cataract extraction with intraocular lens insertion is widely regarded as the treatment best leading to post-surgical improvement in the patient's vision. However, with the increasing use of the 'Nd-YAG laser post capsulotomy' to treat a possible after-cataract following extracapsular cataract extraction, protection of the intraocular lens in the process of that treatment becomes a point at issue. Central to this problem is the degree of separation of the 'laser space' the amount of which was found to be dependent on the inserted lens. Out of total of 122 operations, the absence of a laser ridge on the inserted lens, resulted in the formation of a laser space in only 68.75% of the cases with the average separation being only 0.068mm. Insertion of a lens with a laser ridge, on the other hand, produced a laser space in 100% of the cases with an average separation of some 0.189mm.