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In this era of cutting-edge research and digitalization, artificial intelligence (AI) has rapidly penetrated all subspecialties, including ophthalmology. Managing AI data and analytics is cumbersome, and implementing blockchain technology has made this task less challenging. Blockchain technology is an advanced mechanism with a robust database that allows the unambiguous sharing of widespread information within a business model or network. The data is stored in blocks that are linked together in chains. Since its inception in 2008, blockchain technology has grown over the years, and its novel use in ophthalmology has been less well documented. This section on current ophthalmology discusses the novel use and future of blockchain technology for intraocular lens power calculation and refractive surgery workup, ophthalmic genetics, payment methods, international data documentation, retinal images, global myopia pandemic, virtual pharmacy, and drug compliance and treatment. The authors have also provided valuable insights into various terminologies and definitions used in blockchain technology.
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Purpose: This study was conducted to evaluate the accuracy of intraoperative aberrometry (IA) in intraocular lens (IOL) power calculation and compare it with conventional IOL formulas. Methods: This was a prospective case series. Eyes with visually significant cataract and axial hyperopia (AL <22.0 mm) underwent IA?assisted phacoemulsification with posterior chamber IOL (Alcon AcrySof IQ). Postoperative spherical equivalent (SE) was compared with predicted SE to calculate the outcomes with different formulas (SRK/T, Hoffer Q, Haigis, Holladay 2, Barrett Universal ? and Hill?RBF). Accuracy of intraoperative aberrometer was compared with other formulas in terms of mean absolute prediction error (MAE), percentage of patients within 0.5 D and 1 D of their target, and percentage of patients going into hyperopic shift. Results: Sixty?five eyes (57 patients) were included. In terms of MAE, both Hoffer Q (MAE = 0.30) and IA (MAE = 0.32) were significantly better than Haigis, SRK/T, and Barrett Universal ? (P < 0.05). Outcomes within ±0.5 D of the target were maximum with Hoffer Q (80%), superior to IA (Hoffer Q > IA > Holladay 2 > Hill?RBF > Haigis > SRK/T > Barrett Universal ?). Hoffer Q resulted in minimum hyperopic shift (30.76%) followed by Hill?RBF (38.46%), Holladay 2 (38.46%), Haigis (43.07%), and then IA (46.15%), SRK/T (50.76%) and Barrett Universal ? (53.84%). Conclusion: IA was more effective (statistically significant) in predicting IOL power than Haigis, SRK/T, and Barrett Universal ? although it was equivalent to Hoffer Q. Hoffer Q was superior to all formulas in terms of percentage of patients within 0.5 D of their target refractions and percentage of patients going into hyperopic shift
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Background: Recently, the number of litigations on cataract surgeons has increased. Because of the increasing ambitions of surgeons and demands for a spectacle?free life, the incidence of unhappy patients is at an all?time high. To an ophthalmologist, the fruits of a good surgery are dependent largely on their skills. However, more importantly, the roots of good results of a surgery are laid by a perfect IOL (intraocular lens) power calculation. Inaccurate biometry is one of the major reasons for unhappy patients, especially in some challenging scenarios. Purpose: To hit the bull’s eye, as far as target refraction is concerned, it is necessary to understand the benefits and limitations of currently available cutting?edge technology and formulae and apply them to the cataract surgery practice. The aim of the video is to familiarize modern?day ophthalmologists to these situations to achieve a perfect IOL power calculation. Synopsis: Using a step?by?step approach, we decoded biometry in special scenarios like poor cornea, ocular surface disorders, dry eyes, toric IOL calculation, cases with posterior corneal astigmatism, irregular corneas like keratoconus, pellucid marginal degeneration, post Lasik ectasia and penetrating keratoplasty. In this video we tried to address the solution to these special conditions and how to attain target refraction in such cases. A few more issues are addressed like biometry post retina surgery, very dense cataract where it is difficult to obtain axial length, and cases with extreme axial lengths. Highlights: In this case?based approach, with relevant example, we tried to provide solutions for biometry in tricky scenarios like poor cornea, biometry post refractive surgery, dense cataracts, and cataract post retinal surgery. On following these commandments, not only will the litigations stop but our patients will be happier as well
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AIM: To measure the changes of ocular biological parameters before and after phacoemulsification, and compared the choice of intraocular lens(IOL)power calculation formulas based on the new optical biometric instrument IOL Master 700.METHODS: A prospective study. Clinical data were collected from 52 patients(57 eyes)with cataract at the First Affiliated Hospital of Soochow University from January to June 2021. The axial length(AL), anterior chamber depth(ACD)and corneal curvature(Km)were measured and analyzed before and 3mo after phacoemulsification by IOL Master 700. The target refractive value reserved in the calculation of different IOL formulas and the actual refractive value of the automatic refractor 3mo after phacoemulsification were compared and statistically analyzed.RESULTS: The average values of AL measured before and after phacoemulsification were 24.20±1.86, 24.09±1.86mm, the postoperative AL shortened by 0.11mm, and the ACD values were 3.08±0.44, 4.55±0.36mm(P<0.001), ACD deepened by 1.49mm after phacoemulsification. The Km values were 44.14±1.86, 44.14±1.82D(P>0.05). The refractive error of the results measured by the Barrett Universal Ⅱ formula was the smallest before operation, followed by Holladay Ⅱ and the SRK/T formula, the Holladay Ⅰ formula had the largest error and the difference was statistically significant(P<0.05). CONCLUSION: The AL was shortened and the ACD was deepened after phacoemulsification. A correction factor of 0.1mm is suggested to add when calculating the degree. The Barrett Universal Ⅱ formula has the best predictability in the IOL power calculation formulas, follow by Holladay Ⅱ and SRK/T formula.
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With the improvement of cataract operation, the cataract surgery has become increasingly perfect. The cataract patients show greater expectation for the result of cataract operation. As a result, refractive cataract surgery has become the main trend. Detailed investigations of corneal diseases, lens density, corneal topography, preferable intraocular lens ( IOL ) choice, and IOL power calculation can help us get a better knowledge of preoperative conditions on patients, which can be conducted with pentacam. So we can have a better forecast of post - operative outcome and improve the quality of vision for cataract patients after surgery.
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PURPOSE: To evaluate the accuracy of postoperative refractive outcomes of combined phacovitrectomy for epiretinal membrane (ERM) in comparison to cataract surgery alone. MATERIALS AND METHODS: Thirty-nine eyes that underwent combined phacovitrectomy with intraocular lens (IOL) implantation for cataract and ERM (combined surgery group) and 39 eyes that received phacoemulsification for cataract (control group) were analyzed, retrospectively. The predicted preoperative refractive aim was compared with the results of postoperative refraction. RESULTS: In the combined surgery group, refractive prediction error by A-scan and IOLMaster were -0.305+/-0.717 diopters (D) and -0.356+/-0.639 D, respectively, compared to 0.215+/-0.541 and 0.077+/-0.529 in the control group, showing significantly more myopic change compared to the control group (p=0.001 and p=0.002, respectively). Within each group, there was no statistically significant difference in refractive prediction error between A-scan and IOLMaster (all p>0.05). IOL power calculation using adjusted A-scan measurement of axial length based on the macular thickness of the normal contralateral eye still resulted in significant postoperative refractive error (all p<0.05). Postoperative refraction calculated with adjusted axial length based on actual postoperative central foveal thickness change showed the closest value to the actual postoperative achieved refraction (p=0.599). CONCLUSION: Combined phacovitrectomy for ERM resulted in significantly more myopic shift of postoperative refraction, compared to the cataract surgery alone, for both A-scan and IOLMaster. To improve the accuracy of IOL power estimation in eyes with cataract and ERM, sequential surgery for ERM and cataract may need to be considered.
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Aged , Female , Humans , Male , Biometry/methods , Case-Control Studies , Cataract Extraction , Epiretinal Membrane/surgery , Eye , Lens Implantation, Intraocular , Lenses, Intraocular , Optics and Photonics , Phacoemulsification/methods , Postoperative Period , Refraction, Ocular/physiology , Retrospective Studies , Treatment Outcome , Vision Tests , Visual Acuity , Vitrectomy/methodsABSTRACT
PURPOSE: To report the evaluation and comparison of true corneal power after corneal refractive surgery through ARK, Orbscan II(R), Pentacam and IOL master. METHODS: Target IOL (Intraocular lens) power calculated with the SRK/T formula using SMK (Sungmo Eye Hospital keratometry), which is a new method for measuring corneal refractive power, was compared with the back-calculated ideal IOL power after cataract surgery for 30 eyes that required cataract surgery and had previously undergone refractive surgery. Target IOL powers calculated using 4 systems were compared with IOL power calculated using the clinical history method for 64 eyes that had undergone refractive surgery. RESULTS: Using SMK with the SRK/T formula, the actual refraction was within +/-0.5 diopter (D) of the intended refraction for 63.8% of eyes and within +/-1.0 D for 90.9% of eyes. Compared with target IOL power calculated with the clinical history method, target IOL power calculated by SMK with the SRK/T formula had a difference of 1.95 +/- 0.86 D, which was similar to the results calculated by the Haigis-L formula and by TNP with Haigis. CONCLUSIONS: The method of IOL calculation using SMK with the SRK/T formula showed the best predictability in patients after corneal refractive surgery. Comparatively accurate results were produced in IOL power calculations using the Haigis-L formula, and the TNP with Haigis method.
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Humans , Cataract , Refractive Surgical ProceduresABSTRACT
Background Combination of cataractopiesis with intraocular lens (IOL) is believed to improve the patient' s quality of life. However, 1OL power and axial length measured by traditional method in silicone-filled eye is normally bias to the actual levels. The optical coherence biometry technology has been widely used in the measurement of IOL, but little studies have been conducted to demonstrate the IOL power difference between those methods. Objective This study was to evaluate the predictability of IOL power calculations using the IOLMaster and adjusting contact ultrasound A-scan method in silicone oil-filled eyes. Methods Forty-four silicone-filled eyes of 42 patients were divided into 2 groups according to the intraocular pressure (IOP) ( group A: ≥ 10 mmHg group,29 eyes;group B:＜10 mmHg group, 15 eyes). IOLMaster and ocular ultrasonic measurement were used to measure the axis length before and after silicone oil was removed. The preoperatively measured eye axis and cornea curve were used to calculate the theoretical IOL. Results In normal IOP group ( T≥ 10 mmHg,29 eyes), the precision and stability of IOLMaster for axial length ( AL ) measurements and IOL power calculations were better than adjusted ultrasound A-scan( ZIOLMasterdependent = -2. 236, P = 0. 025 ), although in low IOP group ( T＜ 10 mmHg, 15 eyes),there were too much differences in axial length mesurement and IOL power calculation between the IOLMaster and adjusted ultrasound A-scan, so the post-operative imformation was not predicted accurately. Conclusion For anticipatory normal postoperative IOP eyes, the refractive outcome in cataract surgery in silicone oil-filled eyes can be predicted reliably and accurately with IOLMaster. But for complicated or anticipatory unstable postoperative IOP eyes,secondary implantation of IOL would be better.
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Objective: To evaluate the correlation between the refractive state of an aphakic eye after phacoemulsification and the appropriate intraocular lens (IOL) power for emmetropia. Methods: This was a prospective, noncomparative consecutive case series study conducted in the Department of Ophthalmology, Ramathibodi Hospital, Bangkok, Thailand. A total of 57 patients underwent phacoemulsification with foldable IOL implantation by a single surgeon. The intra-operative autorefraction was performed by another assisting surgeon prior to IOL implantation. The implanted IOL power and 1-month post-operative spherical equivalent (SE) were used to retrospectively calculate the predicted IOL power for emmetropia. The correlation between intra-operative aphakic SE and the predicted IOL power for emmetropia was evaluated. Results: Fifty seven patients with a mean age of 67.53 years (SD = 7.52) were included in the study. A linear relationship between intra-operative aphakic SE and predicted IOL power achieving plano was found with a formula: predicted IOL power (Diopter; D) = 9.416 + 1.107 (intra-operative aphakic SE), when the intra-operative aphakic SE range was + 7.25 to +16.25 D, with A-constant of 118.7. Conclusion: There is a linear relationship between intra-operative aphakic SE and predicted IOL power. Intra-operative autorefraction may be a simple and reliable method for IOL power calculation in cataract surgery.
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PURPOSE: To investigate the predictability of and propose guidelines for intraocular lens (IOL) power calculation in post-cataract surgery patients with prior corneal refractive surgery and suggest the guideline. METHODS: Medical records of 18 eyes of 16 patients were retrospectively evaluated for IOL power calculation predictability using three combinations of METHODS: 1) clinical history method, modified Maloney method, and the Feiz-Mannis method; 2) single-K formula versus double-K formula; and 3) Three IOL formulas (SRK/T, Holladay 1, and Hoffer Q). RESULTS: The clinical history method using the single-K formula with the SRK/T and Holliday 1 formula showed the best predictability, with an absolute error of 0.60+/-0.63 D and 0.74+/-0.60 D, respectively. The Feiz-Mannis method showed a tendency of myopic prediction, whereas the modified Maloney method showed a tendency of hyperopic prediction, especially in the patients with myopia more than 7 D prior to the refractive surgery. The double-K formula, when compared to the single-K formula, prevented hyperopic prediction when used with the clinical history method or modified Maloney method. CONCLUSIONS: IOL power calculation using the clinical history method with SRK/T or Holliday 1 formula showed the best predictability in patients after corneal refractive surgery. IOL power calculation using the modified Maloney method, however, because of the hyperopic prediction tendency, should be used cautiously, especially for patients with myopia of 7 D or more prior to the refractive surgery.
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Humans , Cataract , Eye , Lenses, Intraocular , Medical Records , Myopia , Refractive Surgical Procedures , Retrospective StudiesABSTRACT
PURPOSE: To evaluate the Haigis-L method of IOL Master that does not require preoperative data for intraocular lens (IOL) power calculations and compare the results with other methods requiring preoperative data. METHODS: Fifty eyes of 25 patients who had undergone laser-assisted subepithelial keratectomy (LASEK) and were followed for 1 month or longer were selected for this study. IOL power was calculated by four different methods: clinical history method, Feiz-Mannis method, modified Masket method, and Haigis-L method. RESULTS: The mean calculated IOL powers showed the following results: clinical history method; 23.65D, Feiz-Mannis method; 24.45D, modified Masket method; 22.89D, and Haigis-L method; 23.80D. Each IOL power differed statistically from others (p=0.000). The difference between each method was analyzed by the Bonferroni test, with the Feiz-Mannis method showing the highest result and the modified Masket method, the lowest. The clinical history method and Haigis-L method presented similar results. CONCLUSIONS: For patients without data prior to corneal refractive surgery, the Haigis-L method is as accurate as the clinical history method. Therefore, comparatively accurate results can be produced in IOL power calculations using the Haigis-L method after corneal refractive surgery.
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Humans , Eye , Keratectomy, Subepithelial, Laser-Assisted , Lenses, Intraocular , Refractive Surgical ProceduresABSTRACT
PURPOSE: To report three cases of corneal power estimation for intraocular lens power calculation using Orbscan II videokeratography in eyes with previous corneal refractive surgeries. CASE SUMMARY: In three eyes of three patients with previous corneal refractive surgeries, corneal power values were respectively measured at three, four, five, six mm-diameter zones of total mean, axial, tangential, and optical maps using Orbscan II videokeratography. Then, intraocular lens power values were calculated via the SRK/T formula. After cataract surgeries, back-calculated corneal power (BCK) values were estimated from post-phacoemulsification refraction data, and compared with those measured at three, four, five, six mm-diameter zones of each map in Orbscan II videokeratography. The postoperative refractive values after cataract surgeries were achieved within 1.5D of the target refraction in all eyes by using five mm total axial power and four mm total optical power for intraocular lens power calculation. Orbscan II parameters including three mm, four mm total axial power, and three mm total optical power were the least different from the BCK (0.69+/-0.49D, 1.08+/-0.54D, and 1.10+/-0.44D, respectively). CONCLUSIONS: If historical data are not available, Orbscan II videokeratography can be useful for estimating corneal power for intraocular lens power calculations in patients with previous corneal refractive surgeries.
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Humans , Cataract , Corneal Topography , Eye , Lenses, Intraocular , Refractive Surgical ProceduresABSTRACT
PURPOSE: To study the refractive outcome of cataract surgery employing partial coherence interferometry (PCI) and to compare this outcome with that of A-scan ultrasound in a prospective study of 96 eyes of 96 patients that underwent phacoemulsification with intraocular lens (IOL) implantation. METHODS: The SRK-T formula was employed, using PCI (IOL Master(R): the only commercially available model) and A-scan ultrasound data, to predict patients' implanted IOL power. Four to six weeks after cataract surgery, the refractive outcome was determined, and results from the two different biometry methods were compared. RESULTS: Ninety-six patients (mean age: 67.64, SD: 9.91) underwent phacoemulsification with IOL implantation. The optical axial length obtained using the IOL Master(R) was significantly longer (p<0.001, Student's t-test) than the axial length obtained via by A-scan ultrasound, 24.29 (SD 1.80) mm vs. 24.19 (1.75) mm. When using the IOL Master(R), the mean prediction error (PE; planned target of refraction - postoperative refraction) was 0.30 (0.60) D, and the mean absolute prediction error (APE) was 0.51 (0.44) D. When using A-scan ultrasound, the mean PE was 0.01 (0.64) D, and the mean APE was 0.47 (0.43) D. The difference in mean APE between the two biometry methods was not statistically significant (p=0.236, Wilcoxon signed rank test). Among the eyes with an axial length greater than 25 mm, as determined by A-scan ultrasound, the difference in the mean APE was not statistically significant (0.48 (0.87) vs. 0.58 (0.61), p=0.094). Likewise, among the eyes for which with axial length measured by A-scan ultrasound longer than IOL Master(R), the difference in the mean APE error was not statistically significant, (0.33 (0.30) vs. 0.46 (0.41), p=0.110). CONCLUSIONS: IOL power calculation using the PCI is as accurate as that using A-scan ultrasound for predicting the postoperative refractive state of patients who have undergone cataract surgery.
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Humans , Biometry , Cataract , Hominidae , Interferometry , Lenses, Intraocular , Phacoemulsification , Prospective Studies , UltrasonographyABSTRACT
PURPOSE: To evaluate the agreement between actual corneal power and corneal power using Orbscan II of cataract patients who have undergone refractive surgery. METHODS: We retrospectively evaluated 18 eyes of 14 patients who underwent cataract surgery after refractive surgery. IOL power was targeted for emmetropia retrospectively using the manifest refraction two months after cataract surgery with SRK ll or SRK-T. We evaluated the agreement between actual corneal power and corneal power using 1 mm, 2 mm, 3 mm and 4 mm zone of Orbscan II TOP maps. RESULTS: The actual corneal power of cataract patients who underwent refractive surgery and 1 mm, 2 mm, 3 mm and 4 mm zone of Orbscan II TOP maps shows high agreement. When using a corneal power of 1 mm, 2 mm, 3 mm and 4 mm zone of Orbscan II TOP map, the following estimated refractive powers were observed at a 1 mm zone 0.21+/-0.69D, 2 mm zone 0.14+/-0.70D, 3 mm zone 0.25+/-0.95D and 4 mm zone 0.65+/-0.92D. CONCLUSIONS: The actual corneal power of cataract patients who have undergone refractive surgery and 1 mm, 2 mm, 3 mm and 4 mm zone of Orbscan II TOP maps show high agreement. We recommend selecting a corneal power corresponding to 1 mm or 2 mm zone of Orbscan II TOP maps to avoid hyperopia after cataract surgery.
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Humans , Cataract , Emmetropia , Hyperopia , Refractive Surgical Procedures , Retrospective StudiesABSTRACT
PURPOSE: To evaluate the agreement between actual corneal power and corneal power using Orbscan II of cataract patients who have undergone refractive surgery. METHODS: We retrospectively evaluated 18 eyes of 14 patients who underwent cataract surgery after refractive surgery. IOL power was targeted for emmetropia retrospectively using the manifest refraction two months after cataract surgery with SRK ll or SRK-T. We evaluated the agreement between actual corneal power and corneal power using 1 mm, 2 mm, 3 mm and 4 mm zone of Orbscan II TOP maps. RESULTS: The actual corneal power of cataract patients who underwent refractive surgery and 1 mm, 2 mm, 3 mm and 4 mm zone of Orbscan II TOP maps shows high agreement. When using a corneal power of 1 mm, 2 mm, 3 mm and 4 mm zone of Orbscan II TOP map, the following estimated refractive powers were observed at a 1 mm zone 0.21+/-0.69D, 2 mm zone 0.14+/-0.70D, 3 mm zone 0.25+/-0.95D and 4 mm zone 0.65+/-0.92D. CONCLUSIONS: The actual corneal power of cataract patients who have undergone refractive surgery and 1 mm, 2 mm, 3 mm and 4 mm zone of Orbscan II TOP maps show high agreement. We recommend selecting a corneal power corresponding to 1 mm or 2 mm zone of Orbscan II TOP maps to avoid hyperopia after cataract surgery.
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Humans , Cataract , Emmetropia , Hyperopia , Refractive Surgical Procedures , Retrospective StudiesABSTRACT
PURPOSE: To evaluate the correlation between the conventional method and the clinical history method those determine intraocular lens (IOL) power for cataract surgery in eyes with prior laser in situ keratomileusis (LASIK) in the absence of pre-LASIK data. METHODS: The medical records of 200 eyes in 100 patients who had been treated with LASIK for myopia and were followed up for more than 6 months were reviewed. The IOL powers by conventional method using post-LASIK keratometric value and by clinical history method were compared. RESULTS: The mean values of IOL powers by conventional method, and by clinical history method were +20.00+/-1.48D (+13.74~+23.23D) and +20.79+/-1.28D (+17.27~+24.32D), respectively. The following equation describes the regular relationship between the two METHODS: IOL(CHM) (clinical history method)=0.708*IOL(CM) (conventional method) +6.624 (r=0.816, p<.01). CONCLUSIONS: This equation may offer more accurate IOL power for cataract surgery in eyes with prior LASIK surgery in the absence of pre-LASIK data.
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Humans , Cataract , Keratomileusis, Laser In Situ , Lenses, Intraocular , Medical Records , MyopiaABSTRACT
PURPOSE: To report the difference between the postoperative spherical equivalent (SE) and predictive refraction in patients with cataract and primary angle-closure glaucoma (PACG) following cataract operation. METHODS: (1) This study involved 60 eyes who underwent cataract surgery due to PACG and cataract, and 36 eyes who underwent surgery due to cataract only. We measured the manifest refraction postoperatively for comparision to the target power. (2) The axial length (AL) was measured by the different modes of A-scans(phakic, aphackic modes) in the 38 eyes with cataract. (3) The difference was calculated according to the three IOL power calculation formulas for the 60 eyes who had cataract surgery for coexisting PACG and cataract. RESULTS: The difference between postoperative SE and predictive refraction was -0.61+/-0.91D in the PACG with cataract and +0.08+/-0.43D in eyes with cataract only. There was no difference according to the IOL power calculation formulas or the different modes observed in the measurement of AL. A greater difference was seen in eyes with a short AL and an unmeasurable ACD. CONCLUSIONS: The difference between postoperative SE and predictive refraction increased in eyes with the PACG and cataract over those with cataract only. For cataract operation in these eyes, the choice of a lower power IOL (about 0.5D) may be helpful to reduce this difference, especially for eyes with a short AL (less than 24 mm) and an unmeasurable ACD.
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Humans , Cataract , Glaucoma, Angle-ClosureABSTRACT
PURPOSE: To determine the Orbscan corneal power which gave the best correlation with refraction-derived keratometric value (clinical history method) after LASIK in cataract surgery. METHODS: A total of 38 consecutive eyes of 19 patients who were followed up for at least 1 year after LASIK were included in study. The refraction-derived keratometric values were correlated with Orbscan corneal power within 1, 2, 3, 4, and 5 mm diameter zones of keratometric, anterior and total selections of mean, axial, tangential and optical power maps. RESULTS: The Orbscan corneal power of the 5-mm zone optical power total map gave the best correlation with refraction-derived keratometric value. The following regular relationship in linear regression analysis was derived: RDKV(refraction-derived keratometric value)=0.9 X OPT5(corneal power of Orbscan optical power total map 5-mm zone)+4.941(r=0.883). CONCLUSIONS: These results indicate that the corneal power of the 5-mm zone optical power total map was the most appropriate to calculate IOL power in cataract surgery after LASIK when using Orbscan topography.
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Humans , Cataract , Keratomileusis, Laser In Situ , Linear ModelsABSTRACT
PURPOSE: To compare the accuracy of the intraocular lens (IOL) power calculation of clinical history method, with contact lens overrefraction method or computerized videokeratography method in the eyes with previous radial keratotomy (RK) METHODS: The medical records of 2 patients (3 eyes) who had previous RK, and recent phacoemulsification with posterior chamber lens implantation were retrospectively reviewed. All surgical procedures were performed by one surgeon. The power of implanted IOL was calculated by using clinical history method and SRK/T formula. Keratometric (K) value was measured with contact lens overrefraction and computerized videokeratography method before cataract extraction. Ideal keratometric value was calculated from the final postoperative spherical equivalent and the power of implanted IOL retrospectively, and then compared to K value of each method. RESULTS: Mean differences between the ideal K value and K value was 1.48 diopters in computerized videokeratography method, 2.54 diopters in clinical history method, and 3.65 diopters in contact lens overrefraction method, respectively. CONCLUSIONS: Unintentional hyperopia can be decreased by intentional postoperative myopia and obtaining K value by the computerized videokeratography method in cataract surgery of the eyes with previous radial keratotomy.
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Humans , Cataract Extraction , Cataract , Corneal Topography , Hyperopia , Keratotomy, Radial , Lenses, Intraocular , Medical Records , Myopia , Phacoemulsification , Retrospective StudiesABSTRACT
PURPOSE: We prospectively conducted this study to evaluate the effect of laser in-situ keratomileusis (LASIK) on axial length because axial length is an important varible for IOL power calculation. METHODS: One hundred three eyes of fifty two myopic patients had measurements of axial length, ultrasonic central pachymetric readings and otherwise preoperatively and 3 months after LASIK. RESULTS: The axial length and central corneal thickness were reduced statistically significant 3 months after LASIK by 66+/-0.28 micrometer and 57+/-23 micrometer respectively (P0.05) CONCLUSIONS: But the reduction of axial length after LASIK is so small that very small influence is expected on IOL power calculation for the patient who had previous LASIK. So when preoperative IOL power calculation is done using historical method, post-LASIK axial length can be replaced for pre-LASIK axial length to calculate proper IOL power for cataract surgery.