Vol. 17, No. 2, pp. 143-151, June 2012? da ƒ x, ƒ ù vq k RGP e ³ w ½ 1 w» w Ÿw, 139-743 2 w w Ÿw, 580-712 3ƒ w Ÿw, ½w 621-748 nš (2012 5 14 ), (2012 6 12 ), y (2012 6 16 ) : ƒ x ù ƒ ù, vq kƒ RGP vqw ƒ e(stable centration) w w e š w. : ƒ ù ƒ 0.00~2.75 D x ƒ 29 e ù x ƒ 45 RGP yw vq k, qw vq k, v w vq k jš ƒ e w w. : RGP w e k k. s w e f ƒ f k ƒ m w f ƒ x ù, vq k k ƒ. w ù ƒ x ƒ eù x ƒ w w k ƒ f. : RGP vq k, ù ƒ x eƒ š w RGP œ. : RGP, e, ƒ x, ù, vq k gkp vq ƒ vq k š w e kƒ ƒ w q» wù. e sƒ gkp vq k w w w š š, [1] w wù ƒ k. [2] p, w gkp ƒ w w š, w 3-9 w x ù. w ƒ vq kƒ yw ƒ ƒ ew, w v w ƒ ƒ (corneal staining) w. z w gkp [3] e w š w. gkp e w e w. gkp,, Ÿw, z Ÿw š, Ì gkp p w s,, ƒ x w w w eƒ. RGP(rigid gas permeable) ƒ e ƒ ù w ƒ ù s³ w w RGP ƒ ew ƒ ƒ ƒq eƒ w w e w ƒ ùkû. [4] w, yw(alignment) vq k RGP vq k w ƒ ù ƒ f w x ƒ eù x ƒ š š ƒ ù ƒ xkƒ gkp vq k w w. 20 [5] 252 ƒ xk w x(round) ƒ 14.3%, k x(oval) ƒ 31.3%, eù x(symmetirc bowtie) ƒ 28.6%, eù x(asymmetric bowtie) ƒ 17.5%, x(irregular) ƒ 8.3% š swš RGP w xk ƒ ew w š ƒ w. [6] *Corresponding author: Mijung Park, TEL: +82-2-970-6228, E-mail: mjpark@seoultech.ac.kr 143
144 ³, w,,, ½, w, RGP RGP yw vq k w w ƒ ù ƒ ƒ RGP v z RGP ƒ. gkp ƒ eù k [5] w ƒ w ù gkp yw ww» ƒ v w. RGP ƒ x ù ƒ ù k ƒ w eƒ ƒ š w. w RGP vq kƒ yw vq, q(steep) vq, v (flat) vq ë e w w e ƒ š w. 1. 2011 3 l 10 ¾ ù y x š x wš 20~30 ƒ ù ƒ û, 112 224 ƒ x»(ct- 1000, Shin-Nippon, Japan) 3z ƒ xk d w. 224 ƒ x eù x ƒ x ƒ ƒ ù ƒ 0.00~2.75 D w wš RGP w x x ƒ 29 eù x ƒ 45, 44 74 x w. 2. 1) ƒ x ƒ x»(ct-1000, Shin-Nippon, Japan) 3z ƒ xk d wš axial x ƒ x w, Bogan ƒ xk x, k x, eù x, eù x x ù. [7] 2) x w RGP (AIR,, Korea) silicone acrylate(dk=49) 9.3 mm, Ÿw 8.5 mm, Ì 0.14 mm, 3.00 D š, f 7.30~8.50 mm¾ 0.5 mm. 3) vq k sƒ ƒ š (JP/SO 21, Shin-Nippon Commerce, Japan) ƒ 3z d w z z œw RGP vq ƒ š 1 kwš v ƒ w w. RGP 30 z w v r r w g p w x (US/SL 7F, Topcon, Japan) s ƒ e,, ù w yw k vq q w. yw vq k s [8] š ƒ w yw vq wš yw vq f w. f» Û0.10 mm qw vq( 0.10 mm) v w vq(+0.10 mm) š w. 4) e v ƒ RGP wš w w k z y k š œ» w e (Fig. 1). š e (FASTCAMultima 1024 model 16k, PHOTRON, Japan) w ƒ RGP e wš, [4] Photoshop v (Adobe photoshop 7.0) w v (pixel) wš š e vp w mm y w. œ e (0,0) t š RGP e w ƒ ƒ 3z d w s³ w. w ƒ s w 3.5 mm¾ š w g w ƒ š w. 3. m RGP s w e s³ût r t w, vq k Fig. 1. The centration of spherical RGP lens on cornea.
ƒ x, ƒ ù vq k RGP e 145 sƒw (Prism, Graphpad Software, San Diego, USA). 95%» 0.05 w Tukey HSD z w 0.05 w m w ùkü q w. ù ƒ x eù x ƒ e independent sample t-test w 95%» 0.05 m w q w. [9-11] š 1. w e x x ƒ ƒ v ƒ ù 1.25 D w, eù x ƒ v 0.75~2.75 D ƒ ù ùkü. x eù x ƒ RGP e ƒ» w e. eƒ e w vq kƒ yw ù qw ù v w w. ƒ xk, ù vq k e ƒ ùkû ù m w y (Table 1). Sorbara L. RGP œ ew [12] 9.9 mm w j RGP w w RGP ƒ l RGP» w ¾ w y [4] ƒ ƒ xk, ƒ ù v q k w w RGP w eƒ. RGP ƒ w w y» RGP w e vq k, ƒ x ƒ ù s w w j w ƒw. 2. s w e 1) x ƒ ƒ xkƒ x š ƒ ù ƒ 0~0.50 D v RGP k z vq k s w e w (Fig. 2(a)). y w vq RGP s w e ƒ» w 0.78Û0.30 mm, qw vq w 0.67Û0.24 mm, v w vq w 1.17Û0.25 mm ùkû. qw vqw s w ƒ ƒ¾ ew v w vq w k w. vq k y s w e Tukey m w, qw vq v w vq, yw vq v w vq k m w (Table 2). ƒ ù ƒ 0.75~1.25 D s w e qw vq 0.91Û0.33 mm, yw vq 1.03Û0.43 mm, v w vq k 1.20Û0.42 mm ùkù v w v q e e w š, vq k ƒ ù ƒ 0~0.50 D ƒ w e e w ùkû (Fig. 2(b)). x ƒ yw vq wš ƒ ù w 0~0.50 D ù s w e 0.78Û0.30 mm š, 0.75~1.25 D ù 1.03Û0.43 mm ùkù 0.75~1.25 D ù s w eƒ e e w (Fig. 2). ù yw vq Table 1. The lens centration in vertical direction with the fitting states analyzed by corneal astigmatism and corneal type Corneal type Corneal astigmatism (D) The distance of lens center from corneal apex in vertical direction (mm) One-way ANOVA Alignment fitting Steep fitting Flat fitting p-value Round (n=29) Symmetric bowtie (n=45) 0~0.50 0.64Û0.50 0.66Û0.52 0.67Û0.54 0.987 0.75~1.25 0.61Û0.51 0.36Û0.48 0.36Û0.31 0.215 0.75~1.25 0.17Û0.95 0.38Û0.72 0.30Û0.68 0.749 1.50~2.00 0.46Û0.66 0.56Û0.58 0.54Û0.70 0.910 2.25~2.75 0.23Û0.67 0.39Û0.47 0.25Û0.67 0.740
146 ³, w,,, ½, Fig. 2. The lens centration in horizontal direction on roundtyped cornea by the fitting states (n=29). (a) with-therule corneal astigmatism of 0~0.50 D, (b) with-therule corneal astigmatism of 0.75~1.25 D qw vq s w k ƒ j ù v w vq j ƒ ùkû y w. ƒ xkƒ x vq k s w eƒ e š, ƒ x» w ƒ xk 90% ƒ ƒ» š g š f ù ƒ ƒ ù ƒ 0~0.50 D x ƒ š s³ 0.18 mm, 0.75~1.25 D 0.26 mmƒ f., ƒ š ƒ w gkp ƒ š (Table 3). ƒ š ƒ ƒ ùš w gkp ƒ ew ƒ j ƒw. gkp e eƒ w w w eƒ ûš s k, eƒ š s j k w w s w» e y e w e. w [13] ̃ e y j. w [14-15] e y j ƒ š e ƒ j w ƒ ƒ w v ƒ. 2) eù x ƒ ƒ xkƒ eù x š ƒ ù ƒ 0.75~1.25 D Table 2. The statistical analysis of lens centration in horizontal direction Corneal type Corneal astigmatism (D) One-way ANOVA Tukey's multiple comparison test Comparison p-value Comparison p-value Round (n=29) Alignment vs steep 0~0.50 Steep alignment flat <0.001 *** Steep vs flat Alignment vs flat *** *** 0.75~1.25 0.175 ns - - ns 0.75~1.25 0.120 ns - - Alignment vs steep ns Symmetric bowtie (n=45) 1.50~2.00 Steep 0.002 ** alignment flat 2.25~2.75 <0.001 *** Steep vs flat *** Alignment vs flat ns Alignment vs steep ns Steep vs flat *** Alignment vs flat *** ns, not significantly different from each group compared ** p<0.01, *** p<0.001, significantly different from the horizontal centrations of each group compared by one-way ANOVA and Tukey s multiple comparison
ƒ x, ƒ ù vq k RGP e 147 Table 3. The correlation between the lens centration and the flattest position in cornea Corneal type Corneal astigmatism (D) Location Meridian No. of eye (%) Temporal Central Nasal Radius difference (mm) Round (n=29) 0~0.50 0.75~1.25 The flattest position in cornea 13(86.6) 1(6.7) 1(6.7) Lens centration 15(100.0) 0(0.0) 0(0.0) The flattest position in cornea 13(92.9) 1(7.1) 0(0.0) Lens centration 14(100.0) 0(0.0) 0(0.0) 0.18Û0.11 0.26Û0.12 Symmetric bowtie (n=45) 0.75~1.25 1.50~2.00 2.25~2.75 The flattest position in cornea 12(80) 3(20) 0(0) Lens centration 15(100) 0(0) 0(0) The flattest position in cornea 6(40) 9(60) 0(0) Lens centration 15(100) 0(0) 0(0) The flattest position in cornea 6(40) 9(60) 0(0) Lens centration 15(100) 0(0) 0(0) 0.10Û0.06 0.15Û0.13 0.19Û0.09 (radius of temporal meridian at 3.5 mm away from corneal apex - radius of corneal apex) - (radius of nasal meridian at 3.5 mm away from corneal apex - radius of corneal apex) v RGP s w e q, y v w vq ƒƒ w 0.72Û0.28 mm, 0.95Û0.38 mm, 1.03Û0.55 mm d q vq yw vq, v vq k f w (Fig. 3a). 1.50~2.00 D ƒ ù ƒ š eù x v s w e w q, y v w vq ƒ ƒ w 0.68Û0.28 mm, 0.95Û0.34 mm, 1.14Û 0.35 mm d š(fig. 3b), 2.25~2.75 D ƒ ù ƒ v s w e ƒƒ w 0.71Û0.23 mm, 0.78Û0.30 mm, 1.20Û0.31 mm. 1.5 D ƒ ù ƒ eù x ƒ e qw vq y w vq, v w vq s w k w y w m w k (p=0.002 in 1.50~2.00 cyl.d group, p<0.001 in 2.25~2.75 cyl.d group)(table 2). ù ƒ ù ƒ 1.50~2.00 D v yw v q v w vq s w k 2.25~2.75 D ƒ ù ƒ v v w v q yw vq w s w k ƒ j ƒw v w vq k ƒ ù. w e w w [16] s w e ƒ xk vq k y w. Tomlinson 1,000 ƒ xk d w ƒ e eƒ ƒ 21.3%, ƒ 62.4% 80% ƒ eƒ swš šw. [17] ½[4] w ƒ e ƒ x mw ƒ š w. eù x ƒ ƒ w ùküš e ƒ ƒ ew y w. x ƒ eù x ƒ w ƒ eƒ w. 3) ù x eù x ƒ s w e ƒ x ƒ x eù x ƒ w ƒ ù ƒ 0.75~1.25D ù s w e w. x ƒ y w vq w e ƒ» w 1.03Û0.43 mm š eù x ƒ w 0.95Û0.38 mm x ƒ k j w ù m w (Fig. 4a). x ƒ RGP qw vqw w 0.92Û0.33 mm, eù x ƒ w 0.72Û 0.28 mm ùkù yw vq ƒ ù ƒ x ƒ k ƒ j w ù m w (Fig. 4b). s w k v w
148 ³, w,,, ½, yw vq qw vq x ƒ eù x ƒ ƒ ù v w vq eù x ƒ s ƒ e ƒ j. ƒ x k s w e y w» w w ù ƒ ƒ x ƒ eù x ƒ e w v e ƒ m w ù vq k w w x ƒ RGP ƒ vq e eù x ƒ k j ùkú w. eù x ƒ w ƒ k ew š x ƒ w w» š xk eƒ x. eù x ƒ w k ƒ ƒ k ƒ û w w. wr, w e x ƒ ƒ yw vq wš k ƒ q ù v vq k j ùkù s w e w w ƒ x ù vq k w w j š ƒ. w eù x ƒ vq k v w e sƒ x ƒ w r ùkû eù x ƒ ƒ w w ƒ w (Fig. 4). Fig. 3. The lens centration in horizontal direction on symmetric bowtie-typed cornea by the fitting states (n=45). (a) with-the-rule corneal astigmatism of 0.75~1.25 D, (b) with-the-rule corneal astigmatism of 1.50~2.00 D, (c) with-the-rule corneal astigmatism of 2.25~2.75 D vqw x ƒ s w e w 1.20Û0.42 mm, eù x ƒ 1.03Û0.55 mm ùkù y qw vq k ƒ x ƒ k j w ùkü (Fig. 4c). s w k s³e x ƒ eù x ƒ qw vq ƒ v w vq ƒ f. ƒ v s w e s RGP eƒ ƒ x ù ƒ ù, vq k y ƒ š w. RGP w e vq kù, ƒ x, ù ùkû. RGP s w e ƒ š ƒ w ew ƒ j q. s w e s yw vq qw v q ƒ x ƒ ù v w vq eù x ƒ s ƒ k. w, v w vq k RGP
ƒ x, ƒ ù vq k RGP e 149 Fig. 4. The comparison of lens centrations on round- and symmetric bowtie-typed corneas with the same corneal astigmatism. (a) alignment fitting for corneal astigmatism of 0.75~1.25 D, (b) steep fitting for corneal astigmatism of 0.75~1.25 D, (c) flat fitting for corneal astigmatism of 0.75~1.25 D, Each symbol and circle represent mean of lens centration and standard deviation with the different fittings, respectively. Bowtie stands for symmetric bowtie-typed cornea. E: ear, N: nose, U: up, D: down ƒ ù ƒ f s w k ƒ w. w e vq k v w vq k j k w.,», sww š w ù, mw v qƒ w vq w f w vq kù ƒ xkƒ e w x w w y j ƒ w z ƒ w. w mw ƒ x RGP ƒ š y ƒ w RGP vq ƒ y. 2012 w» w ü w. REFERENCES [1] Brennan NA, Lindsay RG, McCraw K, Young L, Bruce AS, Golding TR. Soft lens movement: temporal characteristics. Optom Vis Sci. 1994;71(6):359-363. [2] Park KA, Mah KC, Lee HJ, Yi MH, Kim YM, Bae HJ. The effects on the fitting characteristics of diameter change in spherical RGP contact lens. Korean J Vis Sci. 2007;9(1): 79-88. [3] Kim JM, Kim SH. Comparison of preference and empirical fit success rates for spheric and aspheric RGP lenses. J Korean Oph Opt Soc. 2008;13(2):9-16. [4] Kim SR, Park SI, Lee SE, Park M. A comparison of lens centrations on cornea with RGP lens fitting by the mea-
150 ³, w,,, ½, sured values using keratometer and corneal topography. J Korean Oph Opt Soc. 2011;16(1):41-50. [5] Park EH, Kim SR, Park M. The comparison of fluorescein patterns between spherical RGP lens and aspherical RGP lens by corneal type and astigmatic degree. J Korean Oph Opt Soc. 2012;17(1):37-45. [6] Kim SR, Gil JY, Park CW, Kim JH, Park M. The analysis of corneal patterns in Korean 20s by corneal topography and corneal radii by astigmatic degree. J Korean Oph Opt Soc. 2011;16(3):273-281. [7] Bogan SJ, Waring GO, 3rd. Ibrahim O, Drews C, Curtis L. Classification of normal corneal topography based on computer-assisted videokeratography. Arch Ophthal. 1990; 108(7):945-949. [8] Chan JS, Mandell RB, Johnson L, Reed C, Fusaro R. Contact lens base curve prediction from videokeratography. Optom Vis Sci. 1998;75(6):445-449. [9] Hogben CA. A practical and simple equivalent for student's T test of statistical significance. J Lab Clin Med. 1964;64(2):815-819. [10] Huck SW, McLean RA. Using a repeated measures ANOVA to analyze the data from a pretest-posttest design: a potentially confusing task. Psychological Bulletin. 1975;82(4): 511-518. [11] Kim SJ. A comparison and study on the results of ANO- COVA for the repeated measure data by general linear model and mixed model. Master thesis. Chonnam National University, Gwangju. 2006;1-30. [12] Sorbara L, Fonn D, Holden BA, Wong R. Centrally fitted versus upper lid-attached rigid gas permeable lenses. Part I. Design parameters affecting vertical decentration. International Contact Lens Clinic. 1996;23(3):99-104. [13] Carney LG, Mainstone JC, Carkeet A, Quinn TG, Hill RM. Rigid lens dynamics: lid effects. CLAO J. 1997;23(1): 69-77. [14] Carney LG, Mainstone JC, Quinn TG, Hill RM. Rigid lens centration: Effects of lens design and material density. International Contact Lens Clinic. 1996;23(1):6-12. [15] Quinn TG, Carney LG. Controlling rigid lens centration through specific gravity. International Contact Lens Clinic. 1992;19(3):84-88. [16] Kim DH, Mah KC, Kim DS, Lee HJ. The movement of RGP contact lens related to blinking velocities. Korean J Vis Sci. 2007;9(2):225-240. [17] Tomlinson A, Schwartz C. The position of the corneal apex in the normal eye. Am J Optom Physiol Opt. 1979; 56(4):236-240. [18] Cardona G, Isern R. Topography-based RGP lens fitting in normal corneas: the relevance of eyelid and tear film attributes. Eye Contact Lens. 2011;37(6):359-364. [19] Nosch DS, Ong GL, Mavrikakis I, Morris J. The application of a computerised videokeratography(cvk) based contact lens fitting software programme on irregularly shaped corneal surfaces. Cont Lens Anterior Eye. 2007; 30(4):239-248.
ƒ x, ƒ ù vq k RGP e 151 A Relationship between Corneal Type, Corneal Astigmatism and Lens Fitting States and the Stable Centration of Spherical RGP Lens Shin Gyu Lim 1, Min Ha Lee 1, Sun Mi Choi 2, Sang Hee Park 3, So Ra Kim 1 and Mijung Park 1, 1 Dept. of Optometry, Seoul National University of Science and Technology, Seoul 139-743, Korea 2 DeptU of Optometry, Jeonbuk Science College, Jeongeup 580-712, Korea 3 DeptU of Ophthalmic Optics, Kaya University, Gimhae 621-748, Korea (Received May 14, 2012: Revised June 12, 2012: Accepted June 16, 2012) Purpose: The present study was conducted to investigate whether there is any difference in the centration of spherical RGP lens on cornea according to corneal types, corneal astigmatism and lens fitting states. Methods: Spherical RGP lens was fitted on 29 eyes of round-typed cornea and 45 eyes of symmetric bowtie-typed cornea with 0.00~2.75 D of corneal astigmatism in alignment, steep or flat. Their lens centrations on cornea were analyzed by taking photographs. Results: The centration of spherical RGP lens in the vertical direction was decentrated to downward direction in all cases, and the degree of decentration was not consistent. The lens centration in horizontal direction was significantly more-decentrated to the temporal meridian as base curve of lens was increased, and the degree of decentration was different according to the corneal type, corneal astigmatism and fitting states. With the same degree of astigmatism, the lens decentration to the temporal meridian was bigger in round-typed cornea than that in symmetirc bowtie-typed cornea. Conclusions: The centration of spherical RGP lens varies depending on lens fitting states, corneal astigmatism, and corneal types. Thus, the consideration of these factors may improve the success rate in RGP lens prescription. Key words: Spherical RGP lens, Lens centration, Corneal type, Corneal astigmatism, Lens fitting states