An Immunohistochemical Study of p53, Cyclin D1 and Cathepsin D Expression in Sinonasal Tumors / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Various host and tumor parameters, particularly the tumor size and lymph node metastasis have been studied in an attempt to evaluate and decide the optimal treatment of the patients with head and neck carcinomas. Moreover, it has been recognized that prognostic parameters can be useful for the evaluation of biological behaviors of malignancy. The p53 is a tumor suppressor gene and cyclin D1 is a cell cycle regulator, essential for G1 phase progression. Cathepsin D is a lysosomal aspartyl endopeptidase which degrades the extracellular matrix and proteoglycan. But there are still controversy in their clinical meanings in sinonasal malignant tumors. The purpose of this study is to assess the roles of p53, cyclin D1 and cathepsin D in sinonasal tumorigenesis. MATERIALS AND METHOD: 27 inverted papilloma (IPs), 5 IPs associated with malignant transformation, and 16 squamous cell carcinoma tissue specimens were investigated by immunohistochemical staining for p53, cyclin D1, and cathepsin D. Clinicopathologic values were compared with the incidence of p53, cyclin D1, cathepsin D expression in sinonasal malignant tumors. RESULTS: p53/cyclin D1 expressions were increased as tumor progressed and these expressions were statistically significant (p< .05). No significant correlations were found among p53, cyclin D1, cathepsin D and other clinicopathologic factors. CONCLUSION: These data suggest that expressions of p53, cyclin D1 and cathepsin D may play an important role in the tumorigenesis and progression of sinonasal malignant tumor sequence. Also, it is suggested that p53/cyclin D1 expressions may be useful variables for the prognostic assessment of sinonasal malignant tumors. However, it is not enough conclude so based on this result alone. Further studies, such as using molecular biological techniques, will be required to determine that p53/cyclin D1 expressions are related to the development or prognosis of sinonasal malignant tumors.

A Case of Basaloid Squamous Cell Carcinoma Extended to the Temporal Bone / 대한이비인후과학회지

Basaloid squamous cell carcinoma (BSCC), an uncommon tumor with predilection for the upper aerodigestive tract, is a distinct variant of squamous cell carcinoma, because of its unique histological features and ominous clinical behavior. Basaloid squamous cell carcinoma is a high-grade variant of squamous cell carcinoma. Reports subsequent to its initial description in 1986 by Wain et al. have confirmed that the head and neck region is the most frequently involved region, with majority of the cases arising in the supraglottic larynx, hypopharynx, tonsil and base of tongue. Other head and neck sites include the palate, buccal cavity, floor of mouth, nasopharynx, trachea, and sinonasal tract. BSCC is not limited to the head and neck region but has also been described in the esophagus, lung, thymus, anus and cervix among other sites. We experienced and treated a case of BSCC extended to the temporal bone with characteristic histopathologic and immunologic features. Therefore, we report here the rare case of BSCC invading the temporal bone with literature.

Study on Immunohistochemical Expression of p53, Epidermal Growth Factor and c-erbB-2 in Squamous Cell Carcinoma of the Head and Neck / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Cell proliferation and differentiation are regulated by growth factors and growth factor receptors. Inappropriate expressions of growth factors and oncogenes may influence the biological and clinical phenotype of tumor. But there are still controversy regarding their clinical attributions in head and neck cancer. The authors evaluated the prognostic significance of p53 protein, EGF and c-erbB-2 expression in the squamous cell carcinoma of head and neck to determine their relationship with the clinicopathologic parameters. MATERIALS AND METHODS: Paraffin embedded tissue specimen from 64 cases of squamous cell carcinomas of head and neck were studied by immunohistochemical staining. RESULT: p53 protein, EGF and c-erbB-2 were expressed 53.1%, 29.7% and 57.8%, respectively, in 64 cases of head and neck cancer. The positive expression of p53 protein was associated closely with T-stage and clinical stage. This expression was statistically significant(P<0.05). There were no significant relationships between the reactivity of EGF, c-erbB-2 and clinical parameters. CONCLUSION: The expressions of p53 protein, EGF and c-erbB-2 could be related to oncogenesis in squamous cell carcinoma of the head and neck. And, the expression of p53 protein can be used as a prognostic factor in head and neck squamous cell carcinoma.

Analysis of Leukotriens Release and Fas/Fas Ligand Expression between Aspirin Sensitive and Non-Aspirin Sensitive Nasal Polyp Patients / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Fas and Fas ligand (Fas-L) interactions mediate apoptosis of eosinophils. It is possible that reduction of Fas/Fas-L or Fas-L expression on eosinophils could induce the eosinophilia seen in Samter's triad. The purpose of this study was to analyse the release of LT and Fas/Fas-L expression pattern following exposure to varying concentrations of aspirin in aspirin sensitive nasal polyp (ASP) and non-aspirin sensitive nasal polyp (NASP) patients. MATERIALS AND METHODS: Twenty NASP patients and 16 ASP patients were recruited. Nine healthy subjects served as normal controls. LT levels and Fas/Fas ligand expressions were analysed by ELISA and flow cytometry. RESULTS: Both NASP and ASP patients showed increased release of LT on aspirin exposure in blood and nasal polyps. But ASP patients showed an even greater release of LT on aspirin exposure in blood as compared to NASP patients (p<0.05). LT release from peripheral blood elements do not necessarily coincide with those results obtained from nasal polyps. Eosinophils in ASP patients have significantly decreased Fas expression when compared to NASP patients (p<0.0001). CONCLUSION: These results suggested the role of LT and eosinophils in aspirin intolerance mechanisms in both blood and nasal polyp tissues. The decreased expression of the Fas receptor or defect of Fas/Fas-L interaction could be an important role in pathogenesis of nasal polyp regardless of their association with aspirin sensitivity.

A Case of Rhabdomyosarcoma Involving Nasal Vestibule / 대한이비인후과학회지

Rhabdomyosarcoma is a highly aggressive and the most common soft tissue sarcoma in children. Sites of involvement include the orbit, the nose, the paranasal sinuses, the oropharynx, soft tissue, the nasopharynx, and the external ear or mastoid; however, the nasal vestibule, in particular, is an uncommon site. Rhabdomyosarcoma in the nasal vestibule has been reported in only one case in the literature so far and has never been reported in Korea. We experienced a case of embryonal rhabdomyosarcoma of the nasal vestibule which was managed with total excision of tumor mass and chemotherapy. We report the case and discuss the therapy and management of this unusual problem.

A Study of Apoptosis in Sinonasal Malignant Tumors : Bcl -2 and Fas-L Expression / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Apoptosis may play a key role in determining the growth, aggressiveness, and therapy responsiveness of tumors. Dysregulation of apoptosis can cause the tumorigenesis of sinonasal malignant tumors. The purpose of this study was to assess apoptosis and the expression of its related proteins, bcl-2 and Fas-L, in the sinonasal malgnant tumors. MATERIALS AND METHODS: The study samples were obtained after surgical removal of 22 cases of inverted papilloma (IPs), 4 cases of IPs associated with squamous cell carcinoma (SCC), 14 cases of SCC in sinonasal cavity and 5 cases of normal inferior turbinate mucosa as a control. Apoptosis was evaluated by analysing DNA fragmentation using the TUNEL method. Bcl-2 and Fas-L expressions were assessed by immunohistochemical staining. RESULTS: Apoptotic index (Al) was decreased progressively from IPs, through IP with SCC to reach the lowest level in SCC (p<0.05). Bcl-2/Fas-L expressions were increased as tumor progressed but Fas-L expression was statistically significant only (p<0.05). An inverse relationship between the Fas-L expression and apoptosis was observed as tumor progressed (p<0.05). No significant correlation was found between AI, expressions of bcl-2/Fas-L and other clinicopathologic factors. CONCLUSIONS: These data suggest that bcl-2/Fas-L expressions are related to apoptosis and tumorigenesis of sinonasal malignant tumors. The inverse tendency between Fas-L expression and apoptosis might be an important role in evading surveillance of the immune system of sinonasal malignant tumors.

Study on Immunohistochemical Cyclin D1 Expression and Flow Cytometric DNA Analysis in Squamous Cell Carcinoma of the Larynx / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Cancer is a disease characterized by deregulation of cell cycle control. During the last decade, many alterations in the signaling pathways that ultimately lead to DNA replication and mitosis have been identified in various tumor types. DNA analysis by flow cytometry is considered to be of prognostic value in squamous cell carcinoma of the head and neck. However, a few and contradictory studies have been made on squamous cell carcinoma of the larynx. Expression of the cell cycle control gene cyclin D1 may, at least in some tumor types, provide a prognostic marker. Cyclin D1 is expressed during the G1 phase of the cell cycle and becomes associated with its catalytic partner CDK4 or CDK6. The authors evaluated the prognostic significance of cyclin D1, DNA ploidy and S-phase fraction (SPF) in the squamous cell carcinoma of the larynx to determine their relationship with the various clinicopathological parameters. MATERIALS AND METHODS: Paraffin embedded tissue specimens from 28 cases of squamous cell carcinoma of larynx were studied by the immunohistochemical method using cyclin Dl antibody and by flow cytometric DNA analysis. RESULT: The positive expression of cyclin D1 protein was 60.7% in squamous cell carcinoma of the larynx. In 28 cases of flow sytometric DNA analysis, 23 cases (82.1%) were diploidy and 5 cases (17.9%) were aneuploidy. The SPF ranged from 0.0% to 83.9% (mean 41.4, median 35.2). The mean SPF of DNA diploid cases was 34.2%, whereas that of DNA aneuploid cases was 74.7%. Expression of cyclin D1 protein was found in 52.2% of the diploid cases and in 100% of the aneuploid cases. This expression was statistically significant (p or = 35.2). The expression of cyclin D1 protein did not correlate with clinical features. CONCLUSION: The expression of cyclin D1 protein may be related with development of squamous cell carcinoma of the larynx, but not correlated with prognostic indicators. In cases of aneuploidy/higher SPF (> or = 35.2), The expression of cyclin Dl protein did not significantly correlate with lymph node metastasis, but showed a high expression rate of cyclin Dl protein. However, these correlations were not sufficient for the prognostic indicators in squamous cell carcinoma of the larynx.

The Clinical Results of Small Pupil Phacoemulsification

Phacoemulsification of cataracts with small pupils would induce serious complications in some instance, but we could perform phacoemulsification and IOL implantation in the posterior chamber without any serious complications.We did not need any iris retractors or adjacent iris surgery.Thirty-one eyes of 28 patients with a pupil diameter equal to or less than 4 mm at the beginning of the procedure were reviewed.We analyzed them in the preoperative ocular problems, the size of pupil and the method of enlargement, the technique of nucleus removal, complications, and vision after six months follow-up.Preoperative pupillary diameter was less than 3 mm in 26 cases (83.9%), the most frequent preoperative ocular problem was uveitis with 19 eyes (61.36%).Removing pupillary membrane, releasing of synechiae and mechanical pupillary stretch followed by viscoelastic injection were effective in pupillary expansion.Central phaco chop technique was effective in small pupil cases.In complications, focal corneal edema in 7 eyes and mild iris damage in 6 eyes during surgery.Postoperatively, fibrinous reaction developed in 8 eyes.Postoperative corrected vision of 0.5 or better was in 15 eyes (48.4%), and 22 eyes (71%)had visual increment by 2 lines or more in the Hann's vision chart.In conclusion, phacoemulsification of cataracts with small pupils could be performed safely without serious complications, even with no iris retractor or iris surgery).

Detection of Epstein-Barr Virus in Laryngeal Squamous Cell Carcinoma / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: The Epstein-Barr virus (EBV) is a human herpes virus which causes certain type of lymphoma and some epithelial neoplasm such as undifferentiated nasopharyngeal carcinoma. However, the role of EBV as a causative factor in other head and neck tumor especially, in laryngeal squamous cell carcinoma is not fully elucidated. The aim of this study was to analyze the relationship between the prescence of EBV in laryngeal squamous cell carcinoma and clinicopathologic characteristics. MATERIALS AND METHODS: 65 cases of laryngeal squamous cell carcinoma were retrieved from formalin-fixed, paraffin-embedded blocks and analyzed for EBV by immunohistochemical staining. Results : The EBV was detected in 26(40%) of the 65 patients with laryngeal squamous cell carcinoma and 2(10%) of the 20 control ases. In 26 cases of EBV-positive patients, 13(46.4%) cases were supraglottic cancer and 13(35.1%) cases were glottic cancer. CONCLUSION: These results suggest that EBV may possibly play an etiologic role in the pathogenesis of laryngeal squamous cell carcinoma.

A Case of Fungal Sphenoidal Sinusitis Involving Optic Nerve

Few have reported fungal sinusitis confined in only sphenoidal sinus which caused orbital complication. Reportedly, early surgical treatment can lead to visual recovery especially in its involvement of optic nerve. We report a patients who was hospitalized due to sudden decrease in visual acuity and headache, and was histopathologically diagnosed as having aspergillosis confined in sphenoid sinus, but failed to show restoration of visual acuity after the operation using nasal endoscope.

A Study on the Expression of Transforming Growth Factor-alpha, Epidermal GrowthFactor and Epidermal Growth Factor Receptor in Thyroid Tumors / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Cell proliferation and differentiation are regulated by growth factors and growth factor receptors. Inappropriate expressions of growth factors and altered responsiveness of growth factor receptors may influence the biological and clinical phenotype of tumor. The purpose of this study is to investigate the relationship between the expressions of TGF-alpha, EGF, EGFR and clinical behaviors in thyroid tumors. MATERIALS AND METHODS: The material consisted of 19 papillary carcinomas, 8 follicular carcinomas, 6 anaplastic carcinomas, 8 follicular adenomas and 5 normal thyroid tissues. The authors performed immunohistochemical staining for TGF-alpha, EGF and EGFR. RESULTS: Positive staining for TGF-alpha was found in 84.2% of papillary carcinomas, 100% of follicular carcinomas, 83.3% of anaplastic carcinomas and 25% of follicular adenomas. EGF was positive in 57.8% of papillary carcinomas, 25% of follicular carcinomas, 0% of anaplastic carcinomas and 25% of follicular adenomas. EGFR was positive in 52.6% of papillary carcinomas, 85.7% of follicular carcinomas, 83.3% of anaplastic carcinomas and 75% of follicular adenomas. There was no statistical relationship between regional lymph node metastasis, primary tumor size, patient's age and positive expression rates for TGF-alpha, EGF and EGFR. CONCLUSION: TGF-alpha expression was statistically higher in the malignant thyroid tumors than in benign thyroid tumors. However, the expression of EGFR was shown to be higher in thyroid tumors than in the normal thyroid tissues, but there was no statistical difference between benign and malignant tumors. EGF expressions demonstrated no statistical significance in thyroid tumors.

Clinical Results of LASIK with Turbokeratotome

We evaluated the result of treating myopia and compound myopic astigmatism in 50 eyes using the SCMD turbokeratotome and Visx 20/20 excimer laser with vision key card system. Manifest and cycloplegic refraction, uncorrectedand spectacle corrected visual acuity, corneal topography, pachymetry, slit lamp microscopy, fundus examination, and applanation tonometry were recorded preoperatively and at 1 week, 1, 2, 3 and 6 months postoperatively. The mean spherical epuivalent was changed from -9.1+/-2.47D to -1.37+/-1.28D at 3 month after surgery. 93.3% of eyes had uncorrected visualacuity of 20/40 or better at 3 months follow-up. No eye had visually significant ecntral cornealhaze. Complications such as over- or under correction, interface metallic debris, astigmatism, corneal erosion, incomplete flap, and total cutted flap were occurred. Conclusively, LASIK has good resuls but it is not complication-free procedure, and there is definitely a learning curve.

Expression of the p53 Protein and Detection of HPV by ISH in Sinonasal Inverted Papilloma / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: The p53 protein is a 53 kD phosphoprotein. It is also one of the early recognition markers of malignancy and can be used to predict the aggressive behaviors of tumor. The human papilloma virus (HPV) is a species-specific, epitheliotrophic, double-stranded DNA virus. The purpose of this study was to evaluate the expression rate of p53, and to investigate whether a correlation exists between the rate of recurrence and the severity of lesion. We also investigated whether p53 expression rate and HPV affect recurrence and carcinogenesis of inverted papilloma. MATERIALS AND METHODS: Twenty-two cases of the inverted papilloma and 6 cases of squamous cell carcinoma arising in the inverted papilloma were used for the study. We used immunohistochemical staining for p53 and performed the molecular study of HPV DNA with in situ hybridization (ISH) on the paraffin embedded materials. RESULTS: 1) The overall expression rate of p53 was 39% (11/28). A significant correlation was observed between p53 protein accumulation and the severity of the lesion (p=0.0015). 2) Seven of 11 patients who tested positive for p53 showed recurrence, whereas two of the 12 patients who tested negative for p53 showed recurrence. There was a correlation between the rates of p53 expression and recurrence (p=0.029). 3) The HPV was detected in four cases (13%) of inverted papilloma. There was no statistical significance between HPV and the rate of recurrence(p=0.147). CONCLUSION: The results demonstate that p53 mutations and HPV may play a role in the oncogenesis of inverted papilloma.

Detection of Epstein-Barr Virus DNA in Oropharynx by Polymerase Chain Reaction / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: The Epstein-Barr virus (EBV) is a human herpes virus which causes infectious mononucleosis and is associated with such human cancers as Burkitt's Lymphoma, Hodgkin's disease, non-Hodgkin's disease, and nasopharyngeal carcinoma. However, the role of EBV as a causative factor in other head & neck tumors is not fully elucidated. This study analyzed the detection rate of Epstein-Barr virus (EBV) in the throat washing samples from pateints with head and neck tumors and non-malignant diseases, as well as from normal subjects. MATERIALS & METHODS: The throat washing samples were collected from 49 patients of head & neck tumors, 52 patients of non-malignant diseases (pharyngitis and tonsillitis) and 24 normal subjects. The EBV DNA was detected by using the EBV (BNRF1)-specific primers & Polymerase Chain Reaction (PCR). RESULT: The EBV DNA was detected in 25 (51%) of the 49 throat washing samples from patients with tumors, as well as 3 (60%) of 5 samples from patients with nasopharyngeal carcinoma, and 22 (50%) of 44 samples from patients with head and neck tumors. The throat wasing samples from 52 patients with non-malignant diseases and 24 samples from healthy subjects were also examined. EBV was detected in 17 (32.7%) of 52 patients with non-malignant diseases and 3 (12.5%) of 24 samples from healthy subjects. CONCLUSION: These data indicate that the EBV may be related to non-malignant diseases and head and neck tumor.

Evaluation for the Accuracy of the SRK/T Formula in PCL Implanted Patients(II): Optimizing, A-Constant

To evaluate the efficacy of optimizing of A-constant, the error in prediction was analyzed in three groups of eyes after posterior chamber lens implantation ; 102 eyes with bag placed, 66 eyes with simple sulcus places, and 25 eyes with sulcus placed with transscleral fixation suture. We compared the predictive accuracy of the SRK/T formula using optimized A-constant (bag-placed, sulcus-placed) derived from the 300 eyes with Holladay and SRK/T using original surgeon factor and A-constant. The SRK/T formula with optimized A-constant has a better mean relative, absolut, and standard error and has a better range of IOL prediction error, which was more accurate than other formulas without optimizing. In this study it is our recommendation that each surgeon use a different optimized A-constants for sulcus or bag placement to enhance the predictability of the postoperative refraction.

Causes of Unsuccessful Visual Outcome after Cataract Surgery

We evaluated preoperative characteristics, intraoperative problems, and postoperative complications among the patients who underwent phacoemulsification and posterior chamber intraocular lens implantation by one surgeon. Eyes with postoperative visual acuity was lower than preoperatively or less than 0.4 on Han`s visual acuity chart were designated Group A, 68 eyes (16.4%), and the remaining eyes were Group B, 46 eyes (83.6%). Preoperative characteristics in Group A were uveitis (16.2%), diabetic retinopathy (13.2%), glaucoma (11.8%), macular abnormality (11.8%), etc. Intraoperative complications, posterior capsule reptures with vitreous loss occurred in 21 eyes (5.1%). 8 eyes (11.8%) of the 21 eyes were Group A, 13 eyes (3.8%) were Group B, and the difference between both groups were statistically significant (p<0.01). Postoperatively, cystoid macular edema was occurred in 12 eyes (2.9%). 11 eyes (16.2%) of 12 eyes were Group A, 1 eye (0.3%) was Group B, and the difference between both groups were statistically significant (p<0.01) and 4 eyes were preceded by posterior capsule rupture. From the above results, we recognized the importance of avoiding posterior capsule rupture with vitreous loss. If it does occur, we recommend that meticulous anterior vitrectomy be performed. Following these guidlines should reduce the rate of unsuccessful cataract sugery.

A Case of Hemangiopericytoma in Nasal Cavity and Paranasal Sinus / 대한이비인후과학회지

Hemangiopericytoma is an uncommon vascular tumor described first by Stout and Murray in 1942. These tumors arise from Zimmerman's pericytes, which are found outside capillaries and postcapillary venules. Although hemangiopericytomas are well characterized, many controversies still exist regarding their malignant potential and management. The hemangiopericytomas usually present as rapidly growing, painless masses. They are usually detected because of their rapid growth, or become symptomatic secondary to compression of adjacent structures. Pain occurs with local invasion or bony metastasis. The hemangiopericytoma in the nasal cavity and paranasal sinus often has local recurrence but appears to be a lower grade malignancy. And wide surgical excision is the treatment of the choice. We report a case of hemangiopericytoma occurred in the right nasal cavity and paranasal sinus treated by median maxillectomy via lateral rhinotomy incision.

Changes in Accommodation and Binocular Vision Change after Excimer Laser Photorefractive Keratectomy

Many patients complain of near vision difficulty after PRK surgery. In the prospective study, we report the effect of PRK surgery for myopia on accommodation and binocular vision. 45 myopic eyes (39 patients, 9 males, 30 females) underwent PRK for myopia. Mean preoperative amplitude of accommodation in moderate degree myopia (group 1 -6.00D in spherical equivalent : range -6.10 ~ -10.75D) was 6.85+/-1.41D. Mean postoperative amplitude of accommodation of group 1 was 8.13+/-1.38D, mean postoperative amplitude of accommodation of group 2 was 7.80+/-1.33D, the difference of both groups were statistically significant(p>0.05). Mean preoperative amplitude of accommodation of all patients was 6.91+/-1.35D, mean postoperative amplitude of accommodation was 7.93+/-1.36D, the difference are statistically significant (p>0.01). 12 of 39 patients complained of near vision difficulty while reading after PRK surgery on their one eye, but 3 of them who underwent PRK surgery on their the other eye noticed the disappearance of near vision difficulty. Stereopsis was tested and 15 of 36 patient lost more than 50 sec/arc of streoacuity. Near vision difficulty was not related to the amount of myopia corrected, not related to the stereoacuity change but seemed to related to their adaptability or their reaction time of accommodation with their operated eyes.

SI-30 NB Silicone IOL Implantation Through 3.2mm Clear Corneal Incision

We examined uncorrected visual acuity, surgically induced astigmatism and complications of 122 eyes underwent cataract surgery with implantation of the AMO Phacoflex SI-30NB. More than 80% of all cases showed uncorrected visual acuity better than 20/40. Temporal incision revealed less surgically induced astigmatism and faster rehabilitation than superior incision. Posterior capsular opacity was found in 14.8%, however Nd-YAG laser capsulotomy was performed in 2.5%. The incidences of contraction of capsular opening and displacement of intraocular lens were 4.9% and 4.1%, respectively. The range of displacement was within 1mm. Conclusively, cataract surgery with implantation of the AMO Phacoflex SI-30NB through clear corneal incision of 3.2mm revealed a low incidence of complication and provided patients rapid visual rehabilitation.

Clinical Result of Excimer Laser Park

We evaluated the effectiveness of photoastigmatic refractive Keratectomy(PARK) by excimer laser on patients with compound myopic astigmatism. Spherocylindrical PARK was performed on 181 myopic eyes with astigmatism(mean spherical equivalent : -6.61 D, range : -1.88~-14.5 D) using the visx excimer laser. The eyes were divided into three groups according to the amount of desired astigmatic correction : Group 1(-0.5~-1.0 D), Group 2(-1.25~3.0 D), and Group 3(-3.25~-5.5 D). Patients were followed up for 6 months. Uncorrected visual acuity at postoperative 6 month, was 0.80+/-0.27 in Group 1, 0.79+/-0.19 and 0.71+/-0.21bin Group 2 and 3 respectively. The mean spherical equivalent refraction was -0.24 D 6 months after PARK. Mean astigmatism was reduced from preoperative -0.85+/-0.51 D to postoperative -0.34+/-0.38 D in Group 1, from -2.08+/-0.65 D to -0.43+/-0.64 D and from -4.42+/-0.63 D to -1.23+/-1.25 D in Group 2 and 3 respectively. We also analyzed the angle of error, magnitude of error, index of success, and coefficient of afjustment by vector analysis. No significant complications were observed during the follow-up period. These results show that PARK by excimer laser was effective in correction of astigmatism. The effect of astigmatic correction in Group 2 and 3 were better than that of Group 1. Group 1 showed overcorrected tendency and Group 2 and 3 showed undercorrected tendency.