Corneal transplantation and concomitant SARS-CoV-2 infection: a case report / Transplante de córnea e infecção concomitante por SARS-CoV-2: relato de caso

ABSTRACT This report was aimed at presenting a case of neurotrophic keratitis and concomitant SARS-CoV-2 infection in a patient who has recently undergone a corneal DALK transplant. One month after corneal transplantation with adequate corneal epithelialization, the patient presented neurotrophic keratitis with a torpid course of the corneal transplant coinciding with a SARS-CoV-2 infection, with an excessive host immune response. In addition, the patient presented a re-positivization of nasopharyngeal polymerase chain reaction of SARS-CoV-2 with past disease after starting treatment with autologous serum eye drops. The implications at the ophthalmological level of SARS-CoV-2 infection may be clarified as the time the illness progresses and we learn more about how it acts. In this case, the disparity of signs and symptoms, the antecedent of corneal surgery, and the possibility of a herpetic infection as a cause of the primary leukoma suggested neurotrophic keratitis. Nonetheless, the involvement of systemic SARS-CoV-2 infection in the process, triggering an excessive host immune response at the corneal level with an increase in inflammatory cytokines must be taken into account. No relationship was found between treatment with autologous serum and re-positivization of nasopharyngeal polymerase chain reaction, presenting the patient a favorable response to treatment.

RESUMO O objetivo deste relato foi apresentar um caso de ceratite neurotrófica e infecção concomitante por SARS-CoV-2 em paciente submetido recentemente a transplante de córnea DALK. Um mês após o transplante de córnea com adequada epitelização da córnea, o paciente apresentou ceratite neurotrófica com curso tórpido do transplante de córnea, coincidindo com infecção por SARS-CoV-2, com resposta imune excessiva do hospedeiro. Além disso, o paciente apresentou repositivização da reação em cadeia da polimerase nasofaríngeo de SARS-CoV-2, com doença pregressa após iniciar tratamento com colírio de soro autólogo. As implicações a nível oftalmológico da infecção por SARS-CoV-2, podem ser esclarecidas à medida que a doença progride e aprendemos mais sobre sua forma de atuação. Neste caso, a disparidade de sinais e sintomas, o antecedente de cirurgia de córnea e a possibilidade de infecção herpética como causa do leucoma primário sugeriram ceratite neurotrófica. No entanto, deve-se levar em consideração o envolvimento da infecção sistêmica por SARS-CoV-2 no processo, desencadeando uma resposta imune excessiva do hospedeiro no nível da córnea, com aumento de citocinas inflamatórias. Não foi encontrada relação entre o tratamento com soro autólogo e a repositivização da reação em cadeia da polimerase nasofaríngea, apresentando ao paciente uma resposta favorável ao tratamento.

Risk of Intraocular Lens Opacification After Endothelial Keratoplasty for Different Intraocular Lens Models: A Retrospective Single-Center Cohort Study.

PURPOSE: The aims of this study were to calculate the specific risk of opacification for different intraocular lens (IOL) models and to determine whether differences exist, even between lenses made of similar acrylic materials. METHODS: This is a retrospective cohort study of all patients who underwent endothelial keratoplasty (EK), either after or in conjunction with cataract surgery, from June 2009 to October 2020 at Fundación Jiménez Díaz Hospital. RESULTS: Three hundred seventy-two eyes of 308 patients with a median follow-up of 856 days [interquartile range (IQR): 384-1570] were included, of which 128 IOLs were hydrophobic, 120 hydrophilic, and 124 unknown. 12.9% of IOLs opacified after a median of 466 days (IQR: 255-743). Visual acuity (VA) was significantly lower in the opacified IOL group [0.51 (IQR: 0.36-1.13)] compared with the nonopacified group [0.22 (IQR: 0.11-0.65)] ( P < 0.001). IOL explantation and exchange was performed in 10 eyes, in which VA improved markedly, from 1.75 (IQR: 0.99-3.00) to 0.60 (IQR: 0.36-0.86) ( P = 0.004). IOL material and opacification events were not independent ( P < 0.001). Significant differences were found between the Akreos ADAPT AO and MI60P models and the Asphina 409M model ( P = 0.022). No significant differences were found in the opacification ratio for hydrophilic IOLs in the clinical diagnosis ( P = 0.11), the type of EK ( P = 0.25), the rebubbling rate ( P = 0.44), or the tamponade used ( P = 0.36). CONCLUSIONS: Hydrophilic lenses should be avoided in patients at risk of requiring EK. It is important to know the probability of opacification of each IOL model to balance risk and benefits when planning an EK procedure because not all lenses opacify equally. Opacification is an unwanted event with a negative impact on VA, making IOL explantation and exchange the only viable treatment, although one that is not without risks.

Optical Evaluation of Intracorneal Ring Segment Surgery in Keratoconus.

Purpose: The purpose of this study was to assess the impact of different intracorneal ring segments (ICRS) combinations on corneal morphology and visual performance on patients with keratoconus. Methods: A total of 124 eyes from 96 patients who underwent ICRS surgery were analyzed and classified into 7 groups based on ICRS disposition and the diameter of the surgical zone (5- and 6-mm). Pre- and postoperative complete ophthalmological examinations were conducted. Corneal geometry, volume, and symmetry were studied. Zernike polynomials were used to build a virtual ray-tracing model to evaluate optical aberrations and the Visual Strehl (VS). Results: ICRS induced significant flattening across the cornea, being more pronounced on the anterior (+0.38 mm, P < 0.001) than on the posterior (+0.15 mm, P < 0.001) corneal radius. Asphericity experienced a larger change for a 6-mm surgical zone diameter (from -1.23 ± 1.1 to -1.86 ± 1.2, P < 0.001) than for a 5-mm zone (from -1.99 ± 1.1 to -2.10 ± 1.5, P = 0.536). Mean astigmatism was reduced by 2.05 D (P < 0.001). Combination four was the most effective in reducing astigmatism. Coma decreased by 30% on average and combination one produced an average reduction by 51% (P < 0.05). Patients experienced significant improvement in visual performance, best corrected visual acuity increased from 0.57 ± 0.21 to 0.69 ± 0.21 and VS changed from 0.049 ± 0.02 to 0.065 ± 0.041. Conclusions: ICRS combinations implanted within 5 mm diameter zone are more effective in flattening the cornea, whereas those implanted on 6 mm diameter are as effective in reducing astigmatism and are a good choice if the asymmetry and the intended flattening are smaller. Combinations with asymmetrical implants are the best option to regularize corneal surface. Translational Relevance: This study uses methods and metrics of optical research applied to daily clinical practice.

Pinhole amniotic membrane for peripheral corneal defects in patients with a single eye or low vision.

AIMS: To describe the efficacy of a new pinhole amniotic membrane placement technique in cases of peripheral epithelial defects in patients with a single eye or low vision in the contrye. METHODS: This technique is based on a small central hole done with a dermatological 3 to 4 mm punch (according to pupillary diameter in mesoscopic conditions) and a continuous suture in the perilimbal cornea to fix the amniotic membrane. We performed this technique in 6 patients. Patients were followed clinical and photographically. RESULTS: No changes in the visual acuity before and after the surgery were observed. During follow-up, a complete re-epithelialization was observed with no need for reinterventions. CONCLUSIONS: Amniotic membrane transplantation is a very useful option in patients with persistent epithelial defects; however, its use is limited by the subsequent visual acuity. The use of the pinhole amniotic membrane technique allows us to treat peripheral persistent corneal lesions without modifying patients' visual acuity. This new technique may become especially useful in patients with functional single eye of low vision in the contralateral eye.

Interaction of Monochromatic and Chromatic Aberrations in Pseudophakic Patients.

PURPOSE: To measure monochromatic aberrations at various wavelengths in eyes implanted with the Clareon monofocal aspheric intraocular lens (IOL) (Alcon Laboratories, Inc., Fort Worth, TX). The authors estimated longitudinal chromatic aberration (LCA), modulation transfer functions (MTFs), and the impact of interactions between chromatic and monochromatic aberrations on retinal image quality. METHODS: Ten patients (age: 68.4 ± 3.21 years) were measured in two experiments: (1) Hartmann-Shack wave aberrations at five visible wavelengths (480 to 700 nm) and (2) best subjective focus at each wavelength. Objective and psychophysical LCAs were obtained from the Zernike defocus and psychophysical best focus, respectively. MTFs were calculated for the closest wavelengths to the peak sensitivity of the three cone classes (S [480 nm], M [555 nm], and L [564 nm]) using the measured aberrations and chromatic difference of focus. The degradation produced by LCA was estimated as the visual Strehl ratio for green divided by the visual Strehl ratio for blue and red. RESULTS: The root mean square for higher order aberrations (HOAs) ranged from 0.0622 to 0.2084 µm (700 nm, 4.3-mm pupil). Monochromatic visual Strehl ratio was above 0.35 in all patients. LCA was 1.23 ± 0.05 diopters (D) (psychophysical) and 0.90 ± 0.11 D (objective). Visual Strehl ratio decreased by a factor ranging from 1.38 to 3.82 on chromatic defocus from green to blue. There was a significant correlation between native visual Strehl ratio and the degradation produced by LCA (ie, visual Strehl555/visual Strehl480). CONCLUSIONS: The Clareon IOL compensates for spherical aberration, with postoperative wave aberrations dominated by astigmatism and other HOAs, being highly subject-dependent. The impact of LCA in blue is largely dependent on the magnitude of monochromatic aberrations. [J Refract Surg. 2020;36(4):230-238.].

Comparison of visual quality and subjective outcomes among 3 trifocal intraocular lenses and 1 bifocal intraocular lens.

PURPOSE: To compare visual quality and subjective outcomes between 3 trifocal intraocular lenses (IOLs) and 1 bifocal IOL. SETTING: Clínica Oftalmológica Martínez de Carneros, Madrid, Spain. DESIGN: Prospective case series. METHODS: This study comprised patients having bilateral phacoemulsification and implantation of an AcrySof IQ PanOptix, AT LISA tri 839MP, FineVision, or Tecnis ZLB00 IOL. Postoperative evaluation included logarithm of the minimum angle of resolution (logMAR) uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and distance-corrected near visual acuity (DCNVA); reading speed; through-focus logMAR visual acuity at 100%, 50%, and 12% contrast; and contrast sensitivity function (CSF) under photopic and mesopic conditions. Subjective outcomes were assessed using the National Eye Institute Visual Function Questionnaire-25 (NEI VFQ-25). RESULTS: The study enrolled 160 patients, 40 in each group. Six months postoperatively, there were no statistically significant between-group differences in the spherical equivalent, UDVA, CDVA, DCNVA, reading performance, or CSF under photopic and mesopic conditions. The defocus curves at 100%, 50%, and 15% of contrast showed that trifocal IOLs, especially the AcrySof PanOptix, had better intermediate performance than the bifocal IOL and comparable outcomes at far and near distances. There were no statistically significant differences in the postoperative NEI VFQ-25 questionnaire scores between the 4 IOL groups. CONCLUSION: The trifocal IOLs provided better intermediate distance vision than the bifocal IOL without compromising distance or near vision.

Estimation of intraocular lens position from full crystalline lens geometry: towards a new generation of intraocular lens power calculation formulas.

In a cataract surgery, the opacified crystalline lens is replaced by an artificial intraocular lens (IOL). To optimize the visual quality after surgery, the intraocular lens to be implanted must be selected preoperatively for every individual patient. Different generations of formulas have been proposed for selecting the intraocular lens dioptric power as a function of its estimated postoperative position. However, very few formulas include crystalline lens information, in most cases only one-dimensional. The present study proposes a new formula to preoperatively estimate the postoperative IOL position (ELP) based on information of the 3-dimensional full shape of the crystalline lens, obtained from quantitative eye anterior segment optical coherence tomography imaging. Real patients were measured before and after cataract surgery (IOL implantation). The IOL position and the postoperative refraction estimation errors were calculated by subtracting the preoperative estimations from the actual values measured after surgery. The proposed ELP formula produced lower estimation errors for both parameters -ELP and refraction- than the predictions obtained with standard state-of-the-art methods, and opens new avenues to the development of new generation IOL power calculation formulas that improve refractive and visual outcomes.

Evaluation of the True Wavefront Aberrations in Eyes Implanted With a Rotationally Asymmetric Multifocal Intraocular Lens.

PURPOSE: Standard evaluation of aberrations from wavefront slope measurements in patients implanted with a rotationally asymmetric multifocal intraocular lens (IOL), the Lentis Mplus (Oculentis GmbH, Berlin, Germany), results in large magnitude primary vertical coma, which is attributed to the intrinsic IOL design. The new proposed method analyzes aberrometry data, allowing disentangling the IOL power pupillary distribution from the true higher order aberrations of the eye. METHODS: The new method of wavefront reconstruction uses retinal spots obtained at both the near and far foci. The method was tested using ray tracing optical simulations in a computer eye model virtually implanted with the Lentis Mplus IOL, with a generic cornea or with anterior segment geometry obtained from custom quantitative spectral-domain optical coherence tomography in a real patient. The method was applied to laser ray tracing aberrometry data at near and far fixation obtained in a patient implanted with the Lentis Mplus IOL. RESULTS: Higher order aberrations evaluated from simulated and real retinal spot diagrams following the new reconstruction approach matched the nominal aberrations (approximately 98%). Previously reported primary vertical coma in patients implanted with this IOL lost significance with the application of the proposed reconstruction. CONCLUSIONS: Custom analysis of ray tracing-based retinal spot diagrams allowed decoupling of the true higher order aberrations of the patient's eye from the power pupillary distribution of a rotationally asymmetric multifocal IOL, therefore providing the appropriate phase map to accurately evaluate through-focus optical quality. [J Refract Surg. 2017;33(4):257-265.].

Description of a new family with cryopyrin-associated periodic syndrome: risk of visual loss in patients bearing the R260W mutation.

OBJECTIVE: The aim of this study was to describe a family with cryopyrin-associated periodic syndrome (CAPS) in which the disease was unveiled after the ophthalmologic evaluation. METHODS: Family and personal histories from each of the patients were recorded. Each underwent a full ophthalmological examination along with the physical examination. The mutational analysis of the NLRP3 gene was performed by means of direct sequencing. RESULTS: The proband was admitted during an episode of unilateral anterior uveitis. She had a history of recurrent red eye and had been suffering episodes of skin rash and arthralgia induced by cold since childhood. At examination, she showed a reticulated corneal mid-stroma. Her mother and her younger sister also suffered from relapsing episodes of skin rash and fever triggered by cold as well as flares of red eye. They had developed premature hearing loss. In both cases, opacities in the corneal mid-stroma were evidenced with a slit lamp. The genetic analysis detected the heterozygous germline p.R260W mutation in the NLRP3 gene in the three women, confirming the diagnosis of CAPS. Treatment with anakinra resulted in complete remission of flares. CONCLUSION: In this family, a structural NLRP3 mutation was associated with classic MuckleWells features of different degrees of severity. Interstitial keratitis with corneal opacification, usually ascribed to neonatal-onset multisystem inflammatory disease, was found. We underscore that ocular involvement in MuckleWells syndrome should be carefully assessed, since it can lead to visual impairment.

Ocular and optical coherence tomography-based corneal aberrometry in keratoconic eyes treated by intracorneal ring segments.

PURPOSE: To analyze corneal and total aberrations using custom-developed anterior segment spectral optical coherence tomography (OCT) and laser ray tracing in keratoconic eyes implanted with intracorneal ring segments (ICRS). DESIGN: Evaluation of technology. Prospective study. Case series. METHODS: Nineteen keratoconic eyes were measured before and after ICRS surgery. Anterior and posterior corneal topographic and pachymetric maps were obtained pre- and postoperatively from 3-dimensional OCT images of the anterior segment, following automatic image analysis and distortion correction. The pupil center coordinates were used as reference for estimation of corneal aberrations. Corneal aberrations were estimated by computational ray tracing on the anterior and posterior corneal surfaces. Total aberrations were measured using a custom-developed laser ray tracing aberrometer. Corneal and total aberrations were compared in 8 eyes pre- and postoperatively for 4-mm pupils. RESULTS: Total and corneal aberrations were highly correlated. Average root mean square of corneal and total high-order aberrations (HOAs) were 0.78 ± 0.35 µm and 0.57 ± 0.39 µm preoperatively, and 0.88 ± 0.36 µm and 0.53 ± 0.24 µm postoperatively (4-mm pupils). The anterior corneal surface aberrations were partially compensated by the posterior corneal surface aberrations (by 8.3% preoperatively and 4.1% postoperatively). Astigmatism was 2.03 ± 1.11 µm preoperatively and 1.60 ± 0.94 µm postoperatively. The dominant HOA aberrations both pre- and postoperatively were vertical coma (Z3(-1)), vertical trefoil (Z3(-3)), and secondary astigmatism (Z4(4)). ICRS decreased corneal astigmatism by 27% and corneal coma by 5%, but on average, the overall amount of HOA did not decrease significantly with ICRS treatment. CONCLUSIONS: OCT is a reproducible technique to evaluate corneal aberrations. OCT-based corneal aberrations and ocular aberrations show a high correspondence in keratoconic patients before and after ICRS implantation. ICRS produced a decrease in astigmatism, but on average did not produce a consistent decrease of HOAs.

Quantitative OCT-based longitudinal evaluation of intracorneal ring segment implantation in keratoconus.

PURPOSE: To characterize the geometrical properties of keratoconic corneas upon intracorneal ring segments (ICRS) implantation, using custom-developed optical coherence tomography (OCT). METHODS: Ten keratoconic corneas were measured pre- and post-ICRS surgery (7, 30, and 90 days). Corneal topographic and pachymetric maps were obtained from three-dimensional (3D) images acquired with OCT, provided with custom algorithms for image analysis, distortion correction, and quantification. The 3D positioning of the ICRS was also estimated longitudinally, relative to the pupil center and iris plane. RESULTS: Preoperatively, the average corneal radii of curvature were 7.02 ± 0.54 mm (anterior) and 5.40 ± 0.77 mm (posterior), and the minimum corneal thickness was 384 ± 60 µm. At 90 days, the average corneal radii of curvature were 7.26 ± 0.53 mm (anterior) and 5.44 ± 0.71 mm (posterior), and the minimum corneal thickness was 396 ± 46 µm. ICRS implantation produced a significant decrease of corneal power (by 1.71 ± 1.83 diopters [D] at 90 days). Corneal irregularities (defined by high order Zernike terms of the corneal elevation maps) and the corneal thickness distribution decreased in some patients and increased in others. The 3D ICRS depth matched the planned ICRS depth well (within 23.93 ± 23.49 µm). On average, ICRS showed an overall tilt of -6.8 ± 2.6° (temporal) and -2.1 ± 0.8° (superior) at 7 days. CONCLUSIONS: Spectral OCT (sOCT) provided with distortion correction and analysis tools, is an excellent instrument for evaluating the changes produced by ICRS in keratoconic corneas, and for analyzing the 3D ICRS position during the follow up. ICRS produced flattening on the anterior corneal surface, although the benefit for corneal surface regularization varied across patients.

Full OCT anterior segment biometry: an application in cataract surgery.

In vivo three-dimensional (3-D) anterior segment biometry before and after cataract surgery was analyzed by using custom high-resolution high-speed anterior segment spectral domain Optical Coherence Tomography (OCT). The system was provided with custom algorithms for denoising, segmentation, full distortion correction (fan and optical) and merging of the anterior segment volumes (cornea, iris, and crystalline lens or IOL), to provide fully quantitative data of the anterior segment of the eye. The method was tested on an in vitro artificial eye with known surfaces geometry at different orientations and demonstrated on an aging cataract patient in vivo. Biometric parameters CCT, ACD/ILP, CLT/ILT Tilt and decentration are retrieved with a very high degree of accuracy. IOL was placed 400 µm behind the natural crystalline lens, The IOL was aligned with a similar orientation of the natural lens (2.47 deg superiorly), but slightly lower amounts (0.77 deg superiorly). The IOL was decentered superiorly (0.39 mm) and nasally (0.26 mm).

Intraocular lens alignment from purkinje and Scheimpflug imaging.

The improved designs of intraocular lenses (IOLs) implanted during cataract surgery demand understanding of the possible effects of lens misalignment on optical performance. In this review, we describe the implementation, set-up and validation of two methods to measure in vivo tilt and decentration of IOLs, one based on Purkinje imaging and the other on Scheimpflug imaging. The Purkinje system images the reflections of an oblique collimated light source on the anterior cornea and anterior and posterior IOL surfaces and relies on the well supported assumption of the linearity of the Purkinje images with respect to IOL tilt and decentration. Scheimpflug imaging requires geometrical distortion correction and image processing techniques to retrieve the pupillary axis, IOL axis and pupil centre from the three-dimensional anterior segment image of the eye. Validation of the techniques using a physical eye model indicates that IOL tilt is estimated within an accuracy of 0.261 degree and decentration within 0.161 mm. Measurements on patients implanted with aspheric IOLs indicate that IOL tilt and decentration tend to be mirror symmetric between left and right eyes. The average tilt was 1.54 degrees and the average decentration was 0.21 mm. Simulated aberration patterns using custom models of the patients eyes, built using anatomical data of the anterior cornea and foveal position, the IOL geometry and the measured IOL tilt and decentration predict the experimental wave aberrations measured using laser ray tracing aberrometry on the same eyes. This reveals a relatively minor contribution of IOL tilt and decentration on the higher-order aberrations of the normal pseudophakic eye.

Change in corneal aberrations after cataract surgery with 2 types of aspherical intraocular lenses.

PURPOSE: To study the effect of cataract surgery through 3.2 mm superior incisions on corneal aberrations with 2 types of monofocal intraocular lenses (IOLs) with an aspherical design. SETTING: Instituto de Optica, Consejo Superior de Investigaciones Científicas, and Fundación Jiménez Díaz, Madrid, Spain. METHODS: Corneal topography of 43 eyes was obtained before and after small corneal incision cataract surgery. Twenty-two eyes had implantation of a Tecnis Z9000 silicone IOL (Advanced Medical Optics) and 21 had implantation of an AcrySof IQ SN60WF acrylic IOL (Alcon Research Labs) using the recommended injector for each IOL type. The intended incision size (3.2 mm) was similar in the 2 groups. Corneal aberrations were estimated using custom-developed algorithms (based on ray tracing) for 10.0 mm and 5.0 mm pupils. Comparisons between preoperative and postoperative measurements and across the groups were made for individual Zernike terms and root-mean-square (RMS) wavefront error. RESULTS: The RMS (excluding tilt and defocus) did not change in the AcrySof IQ group and increased significantly in the Tecnis group with the 10.0 mm and 5.0 mm pupil diameters. Spherical aberration and coma-like terms did not change significantly; however, vertical astigmatism, vertical trefoil, and vertical tetrafoil changed significantly with surgery with the 10.0 mm and 5.0 mm pupil diameters (P<.0005). The induced wave aberration pattern for 3rd- and higher-order aberrations consistently showed a superior lobe, resulting from a combination of positive vertical trefoil (Z(3)(-3)) and negative tetrafoil (Z(4)(4)). The mean vertical astigmatism increased by 2.47 microm +/- 1.49 (SD) and 1.74 +/- 1.44 microm, vertical trefoil increased by 1.81 +/- 1.19 microm and 1.20 +/- 1.34 microm, and tetrafoil increased by -1.10 +/- 0.78 microm and -0.89 +/- 0.68 microm in the Tecnis group and AcrySof IQ group, respectively. There were no significant differences between the corneal aberrations in the 2 postoperative groups, although there was a tendency toward more terms or orders changing statistically significantly in the Tecnis group, which had slightly higher amounts of induced aberrations. CONCLUSIONS: Cataract surgery with a small superior incision induced consistent and significant changes in several corneal Zernike terms (vertical astigmatism, trefoil, and tetrafoil), resulting in a significantly increased overall corneal RMS wavefront error. These results can be used to improve predictions of optical performance with new IOL designs using computer eye models and identify the potentially different impact of incision strategies on cataract surgery.

Optical quality and depth-of-field of eyes implanted with spherical and aspheric intraocular lenses.

PURPOSE: To compare experimental optical performance in eyes implanted with spherical and aspheric intraocular lenses (IOLs). METHODS: Corneal, total, and internal aberrations were measured in 19 eyes implanted with spherical (n=9) and aspheric (n=10) IOLs. Corneal aberrations were estimated by virtual ray tracing on corneal elevation maps, and total aberrations were measured using a second-generation laser ray tracing system. Corneal and total wave aberrations were fit to a Zernike polynomial expansion. Internal aberrations were measured by subtracting corneal from total wave aberrations. Optical performance was evaluated in terms of root-mean-square (RMS) wavefront error and Strehl ratio (estimated from the modulation transfer function). Depth-of-field was obtained from through-focus Strehl estimates from each individual eye. RESULTS: Corneal aberrations increased after IOL implantation, particularly astigmatism and trefoil terms. Third and higher order RMS (and the corresponding Strehl ratio) were significantly better in eyes with aspheric IOLs than with spherical IOLs; however, this tendency was reversed when astigmatism was included. Spherical aberration was not significantly different in eyes with aspheric IOLs, whereas it was significantly positive in eyes with spherical IOLs. Third order aberrations were not significantly different across groups. Depth-of-field was significantly larger in eyes with spherical IOLs. Spherical IOLs showed better absolute optical quality in the presence of negative defocus >1.00 D. CONCLUSIONS: Our study shows a good degree of compensation of the corneal spherical aberration in eyes implanted with aspheric IOLs, as opposed to eyes implanted with spherical IOLs. Other sources of optical degradation, both with aspheric and spherical IOLs, are non-symmetric preoperative corneal aberrations, incision-induced aberrations, and third order internal aberrations. Although best corrected optical quality is significantly better with aspheric IOLs, tolerance to defocus tended to be lower.

Optical aberrations of intraocular lenses measured in vivo and in vitro.

Corneal and ocular aberrations were measured in a group of eyes before and after cataract surgery with spherical intraocular lens (IOL) implantation by use of well-tested techniques developed in our laboratory. By subtraction of corneal from total aberration maps, we also estimated the optical quality of the intraocular lens in vivo. We found that aberrations in pseudophakic eyes are not significantly different from aberrations in eyes before cataract surgery or from previously reported aberrations in healthy eyes of the same age. However, aberrations in pseudophakic eyes are significantly higher than in young eyes. We found a slight increase of corneal aberrations after surgery. The aberrations of the IOL and the lack of balance of the corneal spherical aberrations by the spherical aberrations of the intraocular lens also degraded the optical quality in pseudophakic eyes. We also measured the aberrations of the IOL in vitro, using an eye cell model, and simulated the aberrations of the IOL on the basis of the IOL's physical parameters. We found a good agreement among in vivo, in vitro, and simulated measures of spherical aberration: Unlike the spherical aberration of the young crystalline lens, which tends to be negative, the spherical aberration of the IOL is positive and increases with lens power. Computer simulations and in vitro measurements show that tilts and decentrations might be contributors to the increased third-order aberrations in vivo in comparison with in vitro measurements.