Albumin adsorption to contact lens materials: A review

Contact Lens and Anterior Eye

Volumn 31, Issue 4, 2008, Pages 179-187

  Luensmann, Doerte ^a   Jones, Lyndon ^a  

^a UNIVERSITY OF WATERLOO   (Canada)

Author keywords

Contact lens materials; Protein deposition; Serum albumin

Indexed keywords

BIOMATERIAL; ETHYLENE GLYCOL DIMETHACRYLATE; HUMAN SERUM ALBUMIN; LACTOFERRIN; LYSOZYME; POLYMACON;

ADSORPTION; BACTERIUM ADHERENCE; BIOCOMPATIBILITY; CHEMICAL COMPOSITION; CONFORMATIONAL TRANSITION; CONTACT LENS; HUMAN; HYDROGEL; HYDROPHOBICITY; IONIC STRENGTH; NONHUMAN; PARTICLE SIZE; PH; PHYSICAL CHEMISTRY; PRIORITY JOURNAL; PROTEIN BINDING; PROTEIN CROSS LINKING; PROTEIN INTERACTION; REVIEW; SJOEGREN SYNDROME; SOFT CONTACT LENS; SURFACE PROPERTY; TEAR FILM; TEMPERATURE; WATER CONTENT; WETTABILITY;

ADSORPTION; ANIMALS; CONTACT LENSES; EYE PROTEINS; GLYCOPROTEINS; HUMANS; SERUM ALBUMIN; TEARS;

EID: 47649095644     PISSN: 13670484     EISSN: 14765411     Source Type: Journal    
DOI: 10.1016/j.clae.2008.05.004     Document Type: Review

References (112)

1. Keith D., Hong B., and Christensen M. A novel procedure for the extraction of protein deposits from soft hydrophilic contact lenses for analysis. Curr Eye Res 16 5 (1997) 503-510
2. Brennan N.A., Coles M.L., Comstock T.L., and Levy B. A 1-year prospective clinical trial of balafilcon a (PureVision) silicone-hydrogel contact lenses used on a 30-day continuous wear schedule. Ophthalmology 109 6 (2002) 1172-1177
3. Bohnert J.L., Horbett T.A., Ratner B.D., and Royce F.H. Adsorption of proteins from artificial tear solutions to contact lens materials. Invest Ophthalmol Vis Sci 29 3 (1988) 362-373
4. Baines M.G., Cai F., and Backman H.A. Adsorption and removal of protein bound to hydrogel contact lenses. Optom Vis Sci 67 11 (1990) 807-810
5. Gachon A.M., Bilbaut T., and Dastugue B. Adsorption of tear proteins on soft contact lenses. Exp Eye Res 40 1 (1985) 105-116
6. Tripathi P.C., and Tripathi R.C. Analysis of glycoprotein deposits on disposable soft contact lenses. Invest Ophthalmol Vis Sci 33 1 (1992) 121-125
7. Castillo E.J., Koenig J.L., Anderson J.M., and Lo J. Characterization of protein adsorption on soft contact lenses. I. Conformational changes of adsorbed human serum albumin. Biomaterials 5 6 (1984) 319-325
8. Castillo E.J., Koenig J.L., and Anderson J.M. Characterization of protein adsorption on soft contact lenses IV. Comparison of in vivo spoilage with the in vitro adsorption of tear proteins. Biomaterials 7 2 (1986) 89-96
9. Michaud L., and Giasson C. Comparing the extent of protein build-up on several disposable lenses by two spectrophotometric methods. Cont Lens Anterior Eye 21 4 (1998) 104-108
10. Mannucci L.L., Moro F., Cosani A., and Palumbo M. Conformational state of lacrimal proteins adsorbed on contact lenses. Curr Eye Res 4 6 (1985) 734-736
11. Keith D.J., Christensen M.T., Barry J.R., and Stein J.M. Determination of the lysozyme deposit curve in soft contact lenses. Eye Contact Lens 29 2 (2003) 79-82
12. Brennan N.A., and Coles M.L. Deposits and symptomatology with soft contact lens wear. Int Contact Lens Clin 27 (2000) 75-100
13. Garrett Q., Chatelier R.C., Griesser H.J., and Milthorpe B.K. Effect of charged groups on the adsorption and penetration of proteins onto and into carboxymethylated poly(HEMA) hydrogels. Biomaterials 19 23 (1998) 2175-2186
14. Richard N.R., Anderson J.A., Tasevska Z.G., and Binder P.S. Evaluation of tear protein deposits on contact lenses from patients with and without giant papillary conjunctivitis. Clao J 18 3 (1992) 143-147
15. Moradi O., Modarress H., and Noroozi M. Experimental study of albumin and lysozyme adsorption onto acrylic acid, (AA) and 2-hydroxyethyl methacrylate (HEMA) surfaces. J Colloid Interface Sci 271 1 (2004) 16-19
16. Garrett Q., and Milthorpe B.K. Human serum albumin adsorption on hydrogel contact lenses in vitro. Invest Ophthalmol Vis Sci 37 13 (1996) 2594-2602
17. Garrett Q., Laycock B., and Garrett R.W. Hydrogel lens monomer constituents modulate protein sorption. Invest Ophthalmol Vis Sci 41 7 (2000) 1687-1695
18. Park J.H., and Bae Y.H. Hydrogels based on poly, (ethylene oxide) and poly, (tetramethylene oxide) or poly, (dimethyl siloxane): synthesis, characterization, in vitro protein adsorption and platelet adhesion. Biomaterials 23 8 (2002) 1797-1808
19. Zhang S., Borazjani R.N., Salamone J.C., Ahearn D.G., Crow Jr. S.A., and Pierce G.E. In vitro deposition of lysozyme on etafilcon A and balafilcon A hydrogel contact lenses: effects on adhesion and survival of Pseudomonas aeruginosa and Staphylococcus aureus. Cont Lens Anterior Eye 28 3 (2005) 113-119
20. Jones L., Senchyna M., Glasier M.A., Schickler J., Forbes I., Louie D., and May C. Lysozyme and lipid deposition on silicone hydrogel contact lens materials. Eye Contact Lens 29 1 Suppl (2003) S75-S79 discussion S83-4, S192-4
21. Kingshott P., St John H.A., Chatelier R.C., and Griesser H.J. Matrix-assisted laser desorption ionization mass spectrometry detection of proteins adsorbed in vivo onto contact lenses. J Biomed Mater Res 49 1 (2000) 36-42
22. Lin S.T., Mandell R.B., Leahy C.D., and Newell J.O. Protein accumulation on disposable extended wear lenses. Clao J 17 1 (1991) 44-50
23. Minno G.E., Eckel L., Groemminger S., Minno B., and Wrzosek T. Quantitative analysis of protein deposits on hydrophilic soft contact lenses: I. Comparison to visual methods of analysis. II. Deposit variation among FDA lens material groups. Optom Vis Sci 68 11 (1991) 865-872
24. Pearce D., Tan M.E., Demirci G., and Willcox M.D. Surface protein profile of extended-wear silicon hydrogel lenses. Adv Exp Med Biol 506 Pt B (2002) 957-960
25. Soltys-Robitaille C.E., Ammon Jr. D.M., Valint Jr. P.L., and Grobe III G.L. The relationship between contact lens surface charge and in-vitro protein deposition levels. Biomaterials 22 24 (2001) 3257-3260
26. Bruinsma G.M., Rustema-Abbing M., de Vries J., Stegenga B., van der Mei H.C., van der Linden M.L., Hooymans J.M., and Busscher H.J. Influence of wear and overwear on surface properties of etafilcon A contact lenses and adhesion of Pseudomonas aeruginosa. Invest Ophthalmol Vis Sci 43 12 (2002) 3646-3653
27. Vermeltfoort P.B., Rustema-Abbing M., de Vries J., Bruinsma G.M., Busscher H.J., van der Linden M.L., Hooymans J.M., and van der Mei H.C. Influence of day and night wear on surface properties of silicone hydrogel contact lenses and bacterial adhesion. Cornea 25 5 (2006) 516-523
28. Lorentz H., and Jones L. Lipid deposition on hydrogel contact lenses: how history can help us today. Optom Vis Sci 84 4 (2007) 286-295
29. Maziarz E.P., Stachowski M.J., Liu X.M., Mosack L., Davis A., Musante C., and Heckathorn D. Lipid deposition on silicone hydrogel lenses, part I: quantification of oleic acid, oleic acid methyl ester, and cholesterol. Eye Contact Lens 32 6 (2006) 300-307
30. Spurr-Michaud S., Argueso P., and Gipson I. Assay of mucins in human tear fluid. Exp Eye Res 84 5 (2007) 939-950
31. Yan G., Nyquist G., Caldwell K.D., Payor R., and McCraw E.C. Quantitation of total protein deposits on contact lenses by means of amino acid analysis. Invest Ophthalmol Vis Sci 34 5 (1993) 1804-1813
32. Santos L., Rodrigues D., Lira M., Oliveira M.E., Oliveira R., Vilar E.Y., and Azeredo J. The influence of surface treatment on hydrophobicity, protein adsorption and microbial colonisation of silicone hydrogel contact lenses. Cont Lens Anterior Eye (2007)
33. Subbaraman L.N., Glasier M.A., Senchyna M., Sheardown H., and Jones L. Kinetics of in vitro lysozyme deposition on silicone hydrogel, PMMA, and FDA groups I, II, and IV contact lens materials. Curr Eye Res 31 10 (2006) 787-796
34. Senchyna M., Jones L., Louie D., May C., Forbes I., and Glasier M.A. Quantitative and conformational characterization of lysozyme deposited on balafilcon and etafilcon contact lens materials. Curr Eye Res 28 1 (2004) 25-36
35. Temel A., Kazokoglu H., and Taga Y. Tear lysozyme levels in contact lens wearers. Ann Ophthalmol 23 5 (1991) 191-194
36. Zhou L., Beuerman R.W., Foo Y., Liu S., Ang L.P., and Tan D.T. Characterisation of human tear proteins using high-resolution mass spectrometry. Ann Acad Med Singapore 35 6 (2006) 400-407
37. Sack R.A., Tan K.O., and Tan A. Diurnal tear cycle: evidence for a nocturnal inflammatory constitutive tear fluid. Invest Ophthalmol Vis Sci 33 3 (1992) 626-640
38. Choy C.K., Cho P., Benzie I.F., and Ng V. Effect of one overnight wear of orthokeratology lenses on tear composition. Optom Vis Sci 81 6 (2004) 414-420
39. Sitaramamma T., Shivaji S., and Rao G.N. HPLC analysis of closed, open, and reflex eye tear proteins. Indian J Ophthalmol 46 4 (1998) 239-245
40. de Souza G.A., Godoy L.M., and Mann M. Identification of 491 proteins in the tear fluid proteome reveals a large number of proteases and protease inhibitors. Genome Biol 7 8 (2006) R72
41. Tan K.O., Sack R.A., Holden B.A., and Swarbrick H.A. Temporal sequence of changes in tear film composition during sleep. Curr Eye Res 12 11 (1993) 1001-1007
42. Bilbaut T., Gachon A.M., and Dastugue B. Deposits on soft contact lenses electrophoresis and scanning electron microscopic examinations. Exp Eye Res 43 2 (1986) 153-165
43. Scott G., and Mowrey-McKee M. Dimerization of tear lysozyme on hydrophilic contact lens polymers. Curr Eye Res 15 5 (1996) 461-466
44. Peters T. All about albumin: biochemistry, genetics, and medical applications (1996), Academic Press, San Diego, Calif xx, 432 [2] of plates
45. Tanford C., and Buzzell J.G. The viscosity of aqueous solutions of bovine serum albumin between pH 4.3 and 10.5. J Phys Chem 60 (1956) 225-231
46. Hostmark A.T., Tomten S.E., and Berg J.E. Serum albumin and blood pressure: a population-based, cross-sectional study. J Hypertens 23 4 (2005) 725-730
47. Doweiko J.P., and Nompleggi D.J. Role of albumin in human physiology and pathophysiology. JPEN J Parenter Enteral Nutr 15 2 (1991) 207-211
48. Loeb G.I., and Scheraga H.A. Hydrodynamic and thermodynamic properties of bovine serum albumin at low pH. J Phys Chem 60 (1956) 1633-1644
49. Squire P.G., Moser P., and O'Konski C.T. The hydrodynamic properties of bovine serum albumin monomer and dimer. Biochemistry 7 12 (1968) 4261-4272
50. Carter D.C., and He X.M. Structure of human serum albumin. Science 249 4966 (1990) 302-303
51. Ferrer M.L., Duchowicz R., Carrasco B., de la Torre J.G., and Acuna A.U. The conformation of serum albumin in solution: a combined phosphorescence depolarization-hydrodynamic modeling study. Biophys J 80 5 (2001) 2422-2430
52. Sugio S., Kashima A., Mochizuki S., Noda M., and Kobayashi K. Crystal structure of human serum albumin at 2, 5 A resolution. Protein Eng 12 6 (1999) 439-446
53. He X.M., and Carter D.C. Atomic structure and chemistry of human serum albumin. Nature 358 6383 (1992) 209-215
54. Michnik A., Michalik K., Drzazga Z., and Kluczewska A. Comparative DSC Study of human and bovine serum albumin. J Therm Anal Cal 84 1 (2007) 113-117
55. Kurrat R., Prenosil J.E., and Ramsden J.J. Kinetics of human and bovine serum albumin adsorption at silica-titania surfaces. J Colloid Interface Sci 185 1 (1997) 1-8
56. Miller I., and Gemeiner M. Peculiarities in electrophoretic behavior of different serum albumins. Electrophoresis 14 12 (1993) 1312-1317
57. Fung K., Morris C., and Duncan M. Mass spectrometric techniques applied to the analysis of human tears: a focus on the peptide and protein constituents. Adv Exp Med Biol 506 Pt A (2002) 601-605
58. Bright A.M., and Tighe B.J. The composition and interfacial properties of tears, tear substitutes and tear models. J Br Contact Lens Assoc 16 2 (1993) 57-66
59. Fullard R.J., and Snyder C. Protein levels in nonstimulated and stimulated tears of normal human subjects. Invest Ophthalmol Vis Sci 31 6 (1990) 1119-1126
60. Ng V., and Cho P. The relationship between total tear protein concentrations determined by different methods and standards. Graefes Arch Clin Exp Ophthalmol 238 7 (2000) 571-576
61. Ng V., Cho P., Mak S., and Lee A. Variability of tear protein levels in normal young adults: between-day variation. Graefes Arch Clin Exp Ophthalmol 238 11 (2000) 892-899
62. Bjerrum K.B., and Prause J.U. Collection and concentration of tear proteins studied by SDS gel electrophoresis presentation of a new method with special reference to dry eye patients. Graefes Arch Clin Exp Ophthalmol 232 7 (1994) 402-405
63. Van Bijsterveld O.P., and Janssen P.T. Local antibacterial defense in the sicca syndrome. In: Holly F.J., Lamberts D.W., and MacKeen D.L. (Eds). The preocular tear film in health, disease and contact lens wear (1986), Dry Eye Institute, Inc., Lubbock, Texas 857-864
64. Baleriola-Lucas C., Fukuda M., Willcox M.D., Sweeney D.F., and Holden B.A. Fibronectin concentration in tears of contact lens wearers. Exp Eye Res 64 1 (1997) 37-43
65. Fullard R.J., and Tucker D.L. Changes in human tear protein levels with progressively increasing stimulus. Invest Ophthalmol Vis Sci 32 8 (1991) 2290-2301
66. Mandel I.D., and Stuchell R.N. The lacriamal-salivary axis in health and disease. In: Holly F.J., Lamberts D.W., and MacKeen D.L. (Eds). The preocular tear film in health, disease and contact lens wear (1986), Lubbock, Texas, Dry Eye Institute, Inc. 852-856
67. van Bijsterveld O.P., and Janssen P.T. The effect of calcium dobesilate on albumin leakage of the conjunctival vessels. Curr Eye Res 1 7 (1981) 425-430
68. Lundh R.L., Liotet S., and Pouliquen Y. Study of the human blood-tear barrier and the biochemical changes in the tears of 30 contact lens wearers (50 eyes). Ophthalmologica 188 2 (1984) 100-105
69. Carney F.P., Morris C.A., and Willcox M.D. Effect of hydrogel lens wear on the major tear proteins during extended wear. Aust N Z J Ophthalmol 25 Suppl. 1 (1997) S36-S38
70. Bjerrum K.B. The ratio of albumin to lactoferrin in tear fluid as a diagnostic tool in primary Sjogren's syndrome. Acta Ophthalmol Scand 75 5 (1997) 507-511
71. Taylor R.L., Willcox M.D., Williams T.J., and Verran J. Modulation of bacterial adhesion to hydrogel contact lenses by albumin. Optom Vis Sci 75 1 (1998) 23-29
72. Demirel G., Ozcetin G., Turan E., and Caykara T. pH/temperature - sensitive imprinted ionic poly, (N-tert-butylacrylamide-co-acrylamide/maleic acid) hydrogels for bovine serum albumin. Macromol Biosci 5 10 (2005) 1032-1037
73. Bajpai A.K., and Mishra D.D. Adsorption of a blood protein on to hydrophilic sponges based on poly (2-hydroxyethyl methacrylate). J Mater Sci Mater Med 15 5 (2004) 583-592
74. Dijt J.C., Cohen-Stuart M.A., Hofman J.E., and Fleer G.J. Kinetics of polymer adsorption in stagnation point flow. Colloids Surfaces 51 (1990) 141-158
75. Carter D.C., and Ho J.X. Structure of serum albumin. Adv Protein Chem 45 (1994) 153-203
76. Sasaki Y., Suzuki Y., and Ishibashi T. Fluorescent X-ray interference from a protein monolayer. Science 263 5143 (1994) 62-64
77. Mura-Galelli M.J., Voegel J.C., Behr S., Bres E.F., and Schaaf P. Adsorption/desorption of human serum albumin on hydroxyapatite: a critical analysis of the Langmuir model. Proc Natl Acad Sci U S A 88 13 (1991) 5557-5561
78. Ishiguro R., Yokoyama Y., Maeda H., Shimamura A., Kameyama K., and Hiramatsu K. Modes of conformational changes of proteins adsorbed on a planar hydrophobic polymer surface reflecting their adsorption behaviors. J Colloid Interface Sci 290 1 (2005) 91-101
79. Garrett Q., Griesser H.J., Milthorpe B.K., and Garrett R.W. Irreversible adsorption of human serum albumin to hydrogel contact lenses: a study using electron spin resonance spectroscopy. Biomaterials 20 14 (1999) 1345-1356
80. Peppas N.A. Hydrogels in medicine and pharmacy. (1986), CRC Press, Boca Raton, Fla
81. Peppas N.A., Huang Y., Torres-Lugo M., Ward J.H., and Zhang J. Physicochemical foundations and structural design of hydrogels in medicine and biology. Annu Rev Biomed Eng 2 (2000) 9-29
82. Hoffman A.S. Hydrogels for biomedical applications. Adv Drug Deliv Rev 54 1 (2002) 3-12
83. Vroman L., Adams A.L., Fischer G.C., and Munoz P.C. Interaction of high molecular weight kininogen, factor XII, and fibrinogen in plasma at interfaces. Blood 55 1 (1980) 156-159
84. Mandrusov E., Yang J.D., Pfeiffer N., Vroman L., Puszkin P., and Leonard E.F. Kinetics of protein deposition and replacement from a shear flow. AIChE J 44 2 (1998) 233-244
85. Morrissey B.W. The adsorption and conformation of plasma proteins: a physical approach. Annals of the New York Academy of Sciences 283 1 (1977) 50-64
86. Missirlis Y.F., and Lemm W. Modern aspects of protein adsorption on biomaterials vol. x (1991), Kluwer Academic Publishers, Dordrecht p. 262
87. Park H., and Park K. Biocompatibility issues of implantable drug delivery systems. Pharm Res 13 12 (1996) 1770-1776
88. Ratner B.D. Biomaterials science: an introduction to materials in medicine Blood coagulation and blood-materials interactions (1996), Academic Press, San Diego; London pp. 193-199
89. Pitt W.G., Park K., and Cooper S.L. Sequential protein adsorption and thrombus deposition on polymeric biomaterials. J Colloid Interface Sci 111 2 (1986) 343-362
90. Brynda E., Houska M., Jirouskova M., and Dyr J.E. Albumin and heparin multilayer coatings for blood-contacting medical devices. J Biomed Mater Res 51 2 (2000) 249-257
91. Pokidysheva E.N., Maklakova I.A., Belomestnaya Z.M., Perova N.V., Bagrov S.N., and Sevastianov V.I. Comparative analysis of human serum albumin adsorption and complement activation for intraocular lenses. Artif Organs 25 6 (2001) 453-458
92. Miller M.J., Wilson L.A., and Ahearn D.G. Effects of protein, mucin, and human tears on adherence of Pseudomonas aeruginosa to hydrophilic contact lenses. J Clin Microbiol 26 3 (1988) 513-517
93. Willcox M., Pearce D., Tan M., Demirci G., and Carney F. Contact lenses and tear film interactions. Adv Exp Med Biol 506 Pt B (2002) 879-884
94. Lord M.S., Stenzel M.H., Simmons A., and Milthorpe B.K. The effect of charged groups on protein interactions with poly (HEMA) hydrogels. Biomaterials 27 4 (2006) 567-575
95. Gachon A.M., Bilbault T., and Dastugue B. Protein migration through hydrogels: a tool for measuring porosity-application to hydrogels used as contact lenses. Anal Biochem 157 2 (1986) 249-255
96. Garrett Q., Garrett R.W., and Milthorpe B.K. Lysozyme sorption in hydrogel contact lenses. Invest Ophthalmol Vis Sci 40 5 (1999) 897-903
97. Tighe B. In: Phillips F., and Speedwell L. (Eds). Contact lens materials, in contact lenses (2006), Edinburgh, Butterworth-Heinemann 59-78
98. Barbucci R., Magnani A., and Leone G. The effects of spacer arms in cross-linked hyaluronan hydrogel on Fbg and HSA adsorption and conformation. Polymer 43 12 (2002) 3541-3548
99. Novick S.J., and Dordick J.S. Investigating the effects of polymer chemistry on activity of biocatalytic plastic materials. Biotechnol Bioeng 68 6 (2000) 665-671
100. Gomez C.G., Alvarez Igarzabal C.I., and Strumia M.C. Effect of the crosslinking agent on porous networks formation of hema-based copolymers. Polymer 45 18 (2004) 6189-6194
101. Kita M., Ogura Y., Honda Y., Hyon S.H., Cha II W., and Ikada Y. Evaluation of polyvinyl alcohol hydrogel as a soft contact lens material. Graefes Arch Clin Exp Ophthalmol 228 6 (1990) 533-537
102. Kim J., and Somorjai G.A. Molecular packing of lysozyme, fibrinogen, and bovine serum albumin on hydrophilic and hydrophobic surfaces studied by infrared-visible sum frequency generation and fluorescence microscopy. J Am Chem Soc 125 10 (2003) 3150-3158
103. Abelson M.B., Udell I.J., and Weston J.H. Normal human tear pH by direct measurement. Arch Ophthalmol 99 2 (1981) 301
104. Yamada M., Mochizuki H., Kawai M., Yoshino M., and Mashima Y. Fluorophotometric measurement of pH of human tears in vivo. Curr Eye Res 16 5 (1997) 482-486
105. Curry S., Mandelkow H., Brick P., and Franks N. Crystal structure of human serum albumin complexed with fatty acid reveals an asymmetric distribution of binding sites. Nat Struct Biol 5 9 (1998) 827-835
106. Rodbard D., and Chrambach A. Estimation of molecular radius, free mobility, and valence using polyacylamide gel electrophoresis. Anal Biochem 40 1 (1971) 95-134
107. Wood J.M., Attwood D., and Collett J.H. Characterization of poly, (2-hydroxyethyl methacrylate) gels (1983), Marcel Dekkr, Inc. p. 93-101
108. Gatin E., Alexandreanu D., Popescu A., Berlic C., and Alexandreanu I. Correlations between permeability properties and the pore-size distribution of the porous media "hydron" useful as contact lenses. Phusica Med XVI 1 (1999) 13-19
109. Luensmann D., Glasier M.A., Zhang F., Bantseev V., Simpson T., and Jones L. Confocal microscopy and albumin penetration into contact lenses. Optom Vis Sci 84 9 (2007) 839-847
110. Suwala M., Glasier M.A., Subbaraman L.N., and Jones L. Quantity and conformation of lysozyme deposited on conventional and silicone hydrogel contact lens materials using an in vitro model. Eye Contact Lens 33 3 (2007) 138-143
111. Woods C.A., Jones D.A., Jones L.W., and Morgan P.B. A seven year survey of the contact lens prescribing habits of Canadian optometrists. Optom Vis Sci 84 6 (2007) 505-510
112. Morgan P.B., and Efron N. A decade of contact lens prescribing trends in the United Kingdom (1996-2005). Cont Lens Anterior Eye 29 2 (2006) 59-68