Single-step transepithelial photorefractive keratectomy in myopia and astigmatism: 18-month follow-up
Soheil Adib-MoghaddamSaeed SoleymanjahiBahram SalmanianAmir‐Houshang OmidvariFatemeh Adili-AghdamFarsad NoorizadehMedi Eslani
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Purpose To evaluate the long-term quantitative and qualitative optical outcomes of 1-step transepithelial photorefractive keratectomy (PRK) to correct myopia and astigmatism. Setting Bina Eye Hospital, Tehran, Iran. Design Prospective interventional case series. Methods Eyes with myopia with or without astigmatism were evaluated. One-step transepithelial PRK was performed with an aberration-free aspheric optimized profile and the Amaris 500 laser. Eighteen-month follow-up results for refraction, visual acuities, vector analysis, higher-order aberrations, contrast sensitivity, postoperative pain, and haze grade were assessed. Results The study enrolled 146 eyes (74 patients). At the end of follow-up, 93.84% of eyes had an uncorrected distance visual acuity of 20/20 or better and 97.94% of eyes were within ±0.5 diopter of the targeted spherical refraction. On vector analysis, the mean correction index value was close to 1 and the mean index of success and magnitude of error values were close to 0. The achieved correction vector was on an axis counterclockwise to the axis of the intended correction. Photopic and mesopic contrast sensitivities and ocular and corneal spherical, cylindrical, and corneal coma aberrations significantly improved (all P < .001). A slight amount of trefoil aberration was induced (P < .001, ocular aberration; P < .01, corneal aberration). No eye lost more than 1 line of corrected distance visual acuity. No eye had a haze grade of 2+ degrees or higher throughout the follow-up. Conclusions Eighteen-month results indicate the efficacy and safety of transepithelial PRK to correct myopia and astigmatism. It improved refraction and quality of vision. Financial Disclosure None of the authors has a financial or proprietary interest in any material or method mentioned.Keywords:
Mesopic vision
Astigmatism
Coma (optics)
Emmetropia
Subjective refraction
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This paper deals with the issues of meaning S/P factor of light sources in lighting of outdoor spaces. The first part describes the problem of photopic, scotopic and mesopic vision, as well as functions and activities of the human eye which define the meaning of the S/P factor lamps. The second part is dedicated to the measurement of luminous flux a selected light source used to lighting outdoor spaces, calculating S/P (scotopic/photopic) factor and ELF (Effective Luminance Factors) and finally to drawing conclusions from their measurements and calculations.
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The human eye presents different visual responses for different luminosity conditions. Thus, it can be defined different regimes of operation of the human visual system, like photopic and scotopic regimes, for high and low luminance levels respectively. All the classic photometry is based on the vision sensibility under the photopic regime. However, in several situations, it is common to face intermediate conditions known as mesopic. So, in order to convert photometric quantities between photopic and mesopic regimes, there is an equation in literature that describes the relationship between photopic and scotopic luminous fluxes as a function of the color correlate temperature. However, there are some evidences that this expression does not apply accurately to all technologies of light sources. Thus, this paper presents laboratory data showing that the equation in question does not apply to all lighting technologies, pointing towards a review of that relationship.
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Luminous efficacy
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Abstract Purpose: To compare the effects on visual function and quality of life in cataract patients undergoing cataract surgery between different extended depth of focus (EDOF) lenses, when subjected to different illumination conditions. Methods: Observational, prospective, cross‐sectional pilot study with a total of 31 eyes of 15 patients undergoing uncomplicated phacoemulsification cataract surgery with Tecnis Eyhance, Isopure1.2.3 and Vivity intraocular lenses. All patients underwent a complete preoperative examination. They were also evaluated on different days under mesopic and photopic conditions. Results: Thirty‐one eyes of 15 patients (70.5 ± 8.6) were included in the study. Statistically significant values were obtained when comparing intermediate visual acuity (VA) between mesopic and photopic illumination conditions for the Isopure and Eyhance lenses with a value of 0.021 and the Isopure lens with Vivity with 0.001. In photopic conditions at intermediate distance a significant value was obtained between Vivity and Eyhance with a value of 0.02 and in mesopic conditions at intermediate distance between Vivity and Isopure with a value of 0.001. Between the different lenses, no significant values were obtained between the photopic and mesopic conditions. No significant values were found for pupillometry and halometry in mesopic conditions either. Conclusions: All three intraocular lenses provided excellent distance vision in both photopic and mesopic conditions with no statistically significant differences. But in intermediate distance, significant differences were found between photopic and mesopic conditions between the Isopure lens and the Vivity and Eyhance lenses. Therefore, the Isopure lens has worse intermediate VA values in mesopic than the other lenses. There were also no significant differences in near vision in pupillometry and halometry.
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Mesopic conditions elicit both rod and cone responses, and they are more commonly encountered in daily life than are scotopic conditions; yet visual function outcome measures of mesopic visual acuity (VA) or contrast sensitivity (CS) are rarely evaluated.In retinitis pigmentosa (RP), we explored whether visual reductions in mesopic versus photopic conditions were correlated with cone or rod function, as well as the between-visit test-retest variability in mesopic measures.At each of two visits, 22 RP subjects completed mesopic and photopic ETDRS VA and Pelli-Robson chart CS tests obtained with and without a U23 NoIR 4% transmission filter; testing of perifoveal scotopic cone or rod sensitivity with the AdaptDx; and the Rabin Cone Contrast Test (CCT).A greater CS reduction in mesopic versus photopic conditions was significantly related to absence of scotopic rod function (p = 0.038) or longer self-reported duration of night vision loss (p = 0.044). VA reductions >0.2 logMAR in mesopic versus photopic conditions were significantly related to reduced cone-mediated scotopic sensitivity (p = 0.038). Significant predictors of the CCT ratio of S-cone to M- and L-cone sensitivity were mesopic VA (p = 0.038) and absence of AdaptDx rod function (p = 0.008). Test-retest 95% coefficients of repeatability were not significantly different when comparing between photopic and mesopic tests of VA (0.16 and 0.12 logMAR, respectively) or CS (0.21 and 0.24 logCS, respectively).Perifoveal scotopic rod and cone function measured with the AdaptDx was significantly correlated with mesopic CS and VA, respectively, which had good, acceptable test-retest repeatability; thus, they appear to be suitable outcome measures to monitor mesopic visual function in clinical practice or trials. RP subjects with reduced mesopic VA and no perifoveal rod function had a greater loss of sensitivity for S-cones than for L-/M-cones.
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Purpose: To compare the intraindividual effects of an aspheric intraocular lens (IOL) (Tecnis Z9000, Advanced Medical Optics Inc [AMO]) with a conventional spherical IOL (AcrySof single-piece SA60AT, Alcon Laboratories Inc) on functional vision and higher order aberration. Methods: In this prospective study, 40 eyes of 20 patients presenting for cataract surgery were randomly assigned to receive a spherical IOL (AcrySof one-piece) in one eye and an aspheric IOL (Tecnis) in the contralateral eye. Patients were followed for 3 months postoperatively. The results of sine-wave grating contrast sensitivity, contrast acuity under mesopic and photopic conditions, and higher order aberrations (3rd, 4th, and 5th order, primary spherical and total) root-mean-square (RMS) were compared intraindividually. Results: The postoperative corn e al higher order aberrations were not significantly different between the two IOL groups. Total higher order aberrations, total 4th order, and primary spherical aberrations were significantly lower in the Tecnis group at pupil size >5 mm. Contrast acuity was not significantly different between the two IOL groups under mesopic and photopic conditions. Mean pupil size under mesopic conditions was 4.20 mm and 4.08 mm in the AcrySof and Tecnis groups, respectively. Sine-wave contrast sensitivity test results were slightly better in the Tecnis group at spatial frequencies of 1.5, 3, 6, and 12 cycles per degree, but these differences did not reach statistical significance. Conclusions: Compared to conventional spherical IOL, the Tecnis aspheric IOL significantly reduced total ocular and spherical aberration but did not result in better functional vision under mesopic or photopic conditions. Small pupil size may be a factor, which limits the beneficial effect of aspheric IOLs on visual performance. [ J Refract Surg. 2009;25:265–272.]
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Abstract Purpose To evaluate and compare the visual performance of two simultaneous vision multifocal contact lenses ( CL s). Methods In this cross‐over study design 20 presbyopic subjects were fitted with two different simultaneous vision multifocal CL s (the P ure V ision M ultifocal L ow A dd and A cuvue O asys for P resbyopia) in random order. After 1 month, binocular distance visual acuity ( BDVA ) under photopic (85 cd/m 2 ) and mesopic (3 cd/m 2 ) conditions, binocular near visual acuity ( BNVA ), binocular distance contrast sensitivity function ( CSF ) under photopic and mesopic conditions, binocular near CSF and defocus curve were measured. Subjects were then refitted with the alternative correction and the procedure was repeated. Results Mean BDVA under photopic conditions was similar for the A cuvue O asys for P resbyopia and P ure V ision M ultifocal L ow A dd: 0.01 ± 0.08 and 0.00 ± 0.08 log MAR , respectively ( P = 0.45). Under mesopic conditions the values of BDVA were 0.20 ± 0.58 and 0.11 ± 0.09 log MAR , respectively ( P = 0.005). Mean BNVA was 0.20 ± 0.05 and 0.15 ± 0.08 log MAR for the A cuvue O asys and P ure V ision L ow A dd, respectively ( P = 0.06). Binocular distance CSF testing revealed no statistically significant differences between lenses under photopic, mesopic or near conditions. Both lenses provided a comparable intermediate visual acuity. Conclusions Both simultaneous vision multifocal CL s provided adequate distance visual quality under photopic and mesopic conditions, and better visual acuity was provided under mesopic conditions for the P urevision lens. Both lenses provided adequate visual performance at intermediate distance, but the near visual acuity appears to be insufficient for early presbyopes who require a moderately demanding near visual quality.
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