Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.10.2 (focal adhesion kinase)
 44,029 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We compared the accuracy of keratometry and computerized videokeratography (CVK) for use in intraocular lens calculations. We studied 48 eyes of 45 patients having phacoemulsification and posterior chamber lens implantation. Computerized videokeratography was performed with the EyeSys Corneal Analysis System (ECAS). Using the SRK II, SRK/T, and Holladay formulas, we evaluated predictive accuracy calculated with keratometric values and four values derived from ECAS measurements. For each formula, the use of one of the CVK parameters resulted in lower mean absolute errors between actual and predicted postoperative refractive errors and higher percentages of cases with power prediction errors < 0.5 and < 1.0 diopters. Computerized videokeratography may provide a more accurate corneal curvature value than keratometry for use in intraocular lens calculations.
J Cataract Refract Surg 1993
PMID:Comparison of the accuracy of computerized videokeratography and keratometry for use in intraocular lens calculations. 845 Apr 41

Biometry allows determination of the final refractive outcome following cataract extraction with intraocular lens implantation. We compared the accuracy of axial length measurement performed with the slit-lamp supported biometry probe versus a hand-held technique. The two methods of biometry were performed on 32 patients undergoing endocapsular cataract extraction with lens implantation. One of the methods was selected at random in order to predict implant power for a desired refractive outcome using the SRK-T formula. There was no difference in 'within-subject' variance of axial length measurement between the two methods (t = 1.74, p = 0.091), and there was no difference in refractive outcome when the power calculations for the two techniques were compared (t = 0.12, p = 0.906). The hand-held technique provides a useful alternative method of biometry in 'difficult' patients.
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PMID:A comparison of slit-lamp supported versus hand-held biometry. 894 9

The accuracy of IOL calculation using the SRK II formula was studied in 515 cataract extractions with posterior chamber IOLs. All excessively myopic patients (8 patients) and those where we had predicted an emmetropic postoperative result, from a consecutive series of 994 patients, were included. Preoperatively the patients were divided into different groups according to their refractive status and the mean postoperative refraction was calculated in each group. The mean postoperative refraction increased almost linearly with increasing myopic status. The emmetropic group achieved a mean postoperative refraction of -0.6 D, whilst in the most myopic group mean refraction was -1.8 D. We believe that the SRK II formula is inaccurate for myopic eyes, and that new formulas are needed, taking into account all those factors that make up the dioptric power of an eye.
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PMID:Accuracy of IOL calculation in cataract surgery. 919 64

We reviewed the SRK-II method and introduce a new equation to calculate the intraocular lens (IOL) power for eyes which underwent laser phototherapeutic keratectomy (PTK). The Gullstrand series was used to determine the power and the radius of curvature of planoconvex IOLs which alter the focal point from the cornea to reach the conjugate point on the retina. The radius of anterior corneal curvature (R), axial length (AXL), predicted postoperative anterior chamber depth (ACD), and lens thickness (LT) were employed in the following formula to calculate the IOL refractive power: K = R/7.7, DC = 337. 5/R, VC = 1,000/DC*1.336 where VC is the posterior vertex focal length. A1 = -(VC-ACD), B1 = AXL-0.5* K-ACD-0. 103 LT, S = 1/A1 + 1/B1; this determined the diopter (D) of IOL in liquid to be (D) = 1,000/(1/S)* 1.336. In eyes which underwent PTK, the keratometric value prior to cataract surgery was not applied. Instead, R' defined as R-dT, where R is the radius of corneal curvature prior to PTK and dT the amount of corneal tissue removed, was introduced. Further, the corneal thickness before cataract surgery (CT') was defined as CT-dT where CT is the corneal thickness prior to PTK. Although it is important to select a lens that has an acurate predicted anterior chamber depth, the new equation appears to be more useful than the SRK-II formula.
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PMID:[Trial of new intraocular lens power calculation following phototherapeutic keratectomy]. 978 57

We present one case in which phacoemulsification was performed seven years after radial keratotomy (RK). A 55-year-old military police officer had undergone successful bilateral RK for the correction of myopia seven years before he developed a cataract in his left eye. Pre-RK keratometric and refractive data and post-RK myopia reduction were not available. We relied upon corneal topography to measure corneal refractive power. We took the Effective Refractive Power (EffRP) index from EyeSys Holladay's Diagnostic Summary and used SRK-T formula for IOL calculation. A-scan axial length readings were consistent and reliable (AL = 26.0 mm). Aiming at postoperative emmetropia, we implanted a +20D PC IOL (A cost. = 118) was implanted. The lens was expected (SRK-T formula) to give a -1.35D postoperative refraction. After uneventful cataract surgery, corneal topography showed significant corneal instability with central corneal flattening in the first postoperative weeks, mild central corneal steepening at week 6, and return to preoperative corneal curvature at week 23. One year after cataract extraction, the patient's spherical equivalent is +1.12D, showing a prediction error of about 2.5 diopters.
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PMID:Corneal topography and postoperative refraction after cataract phacoemulsification following radial keratotomy. 1003 12

A 79-year-old man with symmetrical microcornea and a dense unilateral nuclear sclerotic cataract had cataract extraction by phacoemulsification. The SRK/T formula suggested a 10.0 diopter (D) intraocular lens (IOL) for emmetropia (axial length 26.58 mm). The non-cataract eye required a 25.0 D IOL for emmetropia (axial length 21.51 mm). Biometric measurements were rechecked, and an 18.0 D IOL was implanted (axial length 24.02 mm). The 6 week postoperative refraction of -13.0 + 2.0 x 25 necessitated IOL exchange (10.0 D). Six weeks postexchange, the refraction was -3.75 + 2.5 x 30. This illustrates that symmetrical anterior microphthalmos does not always coexist with symmetrical posterior microphthalmos. Awareness of the association of symmetrical microcornea and unilateral colobomatous macrophthalmia may aid appropriate IOL selection in future cases.
J Cataract Refract Surg 1999 Jul
PMID:Bilateral microcornea and unilateral macrophthalmia resulting in incorrect intraocular lens selection. 1040 83

With the increasing number of keratorefractive surgical procedures, an increasing number of cataract surgeries in eyes after keratorefractive surgery is anticipated within a few decades. Although cataract extraction seems to be feasible without major technical obstacles, intraocular lens (IOL) power calculation turned out to be problematic. Insertion of the measured average K-readings (= "central corneal power" = keratometric diopters) after myopic radial keratotomy (RK), photorefractive keratectomy (PRK), or laser in situ keratomileusis (LASIK) into standard IOL power-predictive formulas commonly results in substantial undercorrection and postoperative hyperopic refraction or anisometropia. In this article, the major reasons for IOL power miscalculations (which are different for RK versus RRK/LASIK) are discussed based on model calculations and based on case series of cataract surgeries, methods for improved assessment of keratometric diopters as the major underlying problem are exemplary illustrated, and finally a clinical step-by-step approach to minimize IOL power miscalculations status after corneal refractive surgery is suggested. The "clinical history method" (i.e., subtraction of the spherical equivalent [SEQ] change after refractive surgery from the original K-reading) should be applied whenever refraction and K-reading before the keratorefractive procedure are available to cataract surgeons. In addition, more than one modern third-generation formula (e.g., Haigis, Hoffer Q, Holladay 2, or SRK/T) but not a regression formula (e.g., SRK I or SRK II) should be applied and the highest resulting IOL power should be used for the implant.
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PMID:Intraocular lens calculations status after corneal refractive surgery. 1072 26

Intracapsular clear crystalline lens extraction and intraocular lens (IOL) implantation were performed in 4 highly myopic eyes of 2 patients with Marfan's syndrome. One eye of each patient received an anterior chamber IOL and the other, a scleral-fixated posterior chamber IOL. The preoperative spherical equivalent ranged between -14.50 and -28.00 diopters (D) and axial length range, between 25.32 and 36.02 mm. The SRK II formula was used. Mean uncorrected visual acuity improved from counting fingers to 20/80. Postoperative spherical equivalent correction ranged from -0.75 to +2.75 D. One eye had vitreous loss that was managed by anterior vitrectomy. Modern surgery for cataract and management of its complications suggest that clear crystalline lens extraction and IOL implantation can be attempted in selected cases with Marfan's syndrome.
J Cataract Refract Surg 2000 May
PMID:Clear lens extraction and intraocular lens implantation in Marfan's syndrome. 1083 13

Purpose: Conventional methods (such as the SRK-II formula) do not accurately calculate the power of the intraocular lens (IOL) after refractive surgery. Therefore, we compared a new formula including a ray tracing method to the conventional method for foldable IOL lens implantation.Method: Foldable IOLs (MA 60 BM) were implanted in 26 patients (32 eyes) using the phakoemulsification technique. The power of the IOL was measured preoperatively using the SRK-II formula in all cases. From the results of postoperative refractive errors of these cases, the power of IOL calculated by the ray tracing method was compared to the SRK-II formula. Cataract patients first treated with photorefractive keratectomy (PRK) received IOL implants using our ray tracing method and their postoperative refraction was measured.Results: The average postoperative refractive error was 1.32 D in SRK-II formula, 0.95 D in the ray tracing method with Ray 1 used and 0.89 D with Ray 2 used. Postoperative refraction of both eyes first treated with PRK was -1.00 D.Conclusion: The average postoperative refractive error was reduced in the ray tracing method using Olsen's predicted ACD (Ray 2) compared to SRK-II formula. This new tracing method appears to be useful for determination of IOL power and it may be applied for IOL calculation for cataract surgery after refractive surgery.
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PMID:Intraocular Lens Calculation for Cataract Treated with Photorefractive Keratectomy Using Ray Tracing Method. 1103 57

This retrospective study evaluates visual (functional) and refractive outcome of correcting hyperopia (i.e. 2.5 D or more) by means of a cataract procedure and simultaneously the pre-existing clinical significant astigmatism (1.5 D or more with the rule; 1 D or more against the rule), if present, by means of an arcuate keratotomy. Nine eyes undergoing clear lens extractions with intraocular lensimplantation (IOL) in combination with arcuate keratotomy (group one) and 29 eyes without arcuate kertotomy (group two) are included in the study. The mean age at the time of surgery was 62.89 years (range, 50 to 83) in group one and 68.17 years (range, 53 to 86) in group two. For calculation of the lens power a modified SRK II program, aiming at emmetropia was used. In only one highly hyperopic patient the Holladay I formula was used to calculate two piggyback lenses. A modified Istre nomogram was used to determine the surgical parameters of the arcuate keratotomy. The Cravy formula and the Holladay, Cravy, Koch vector analysis were used to determine the change in refractive cylinder results. Patients were followed postoperatively for a mean of 2.8 months in group one and 7.5 months in group two. In group one, 6 out of 9 eyes achieved a postoperative refraction within +/- 0.5 D of intended refraction and 8 out of 9 were within +/- 1 D of intended refraction. In group two, it was 15/29 and 24/29 respectively. Postoperatively, the uncorrected visual acuity was 20/40 or better in all eyes of group one (9/9) and in 27/29 eyes of group two. None of the eyes in both groups lost two or more lines of the best corrected visual acuity. Clear lens extraction with IOL is an effective and safe procedure for the correction of hyperopia in a presbyopic age group. In combination with an arcuate keratotomy, pre-existing astigmatism can be corrected simultaneously.
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PMID:Clear lens extraction to correct hyperopia in presbyopic eyes with or without arcuate keratotomy for pre-existing astigmatism. 1112 73


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