Location Of Intraocular Lens Research Articles

Complications Occurring Through 5 Years Following Primary Intraocular Lens Implantation for Pediatric Cataract

Lensectomy with primary intraocular lens (IOL) implantation is often used in the management of nontraumatic pediatric cataract, but long-term data evaluating the association of age and IOL location with the incidence of complications are limited. To describe the incidence of complications and additional eye surgeries through 5 years following pediatric lensectomy with primary IOL implantation and association with age at surgery and IOL location. This prospective cohort study used Pediatric Eye Disease Investigator Group cataract registry data from 61 institution- and community-based practices over 3 years (June 2012 to July 2015). Participants were children younger than 13 years without baseline glaucoma who had primary IOL implantation (345 bilateral and 264 unilateral) for nontraumatic cataract. Data analysis was performed between September 2021 and January 2023. Lensectomy with primary IOL implantation. Five-year cumulative incidence of complications by age at surgery (<2 years, 2 to <4 years, 4 to <7 years, and 7 to <13 years) and by IOL location (sulcus vs capsular bag) were estimated using Cox proportional hazards models. The cohort included 609 eyes from 491 children (mean [SD] age, 5.6 [3.3] years; 261 [53%] male and 230 [47%] female). Following cataract extraction with primary IOL implantation, a frequent complication was surgery for visual axis opacification (VAO) (cumulative incidence, 32%; 95% CI, 27%-36%). Cumulative incidence was lower with anterior vitrectomy at the time of IOL placement (12%; 95% CI, 8%-16%) vs without (58%; 95% CI, 50%-65%), and the risk of undergoing surgery for VAO was associated with not performing anterior vitrectomy (hazard ratio [HR], 6.19; 95% CI, 3.70-10.34; P < .001). After adjusting for anterior vitrectomy at lens surgery, there were no differences in incidence of surgery for VAO by age at surgery (<2 years, HR, 1.35 [95% CI, 0.63-2.87], 2 to <4 years, HR, 0.86 [95% CI, 0.44-1.68], 4 to <7 years, HR, 1.06 [95% CI, 0.72-1.56]; P = .74) or by capsular bag vs sulcus IOL fixation (HR, 1.22; 95% CI, 0.36-4.17; P = .75). Cumulative incidence of glaucoma plus glaucoma suspect by 5 years was 7% (95% CI, 4%-9%), which did not differ by age after controlling for IOL location and laterality. In this cohort study, a frequent complication following pediatric lensectomy with primary IOL was surgery for VAO, which was associated with primary anterior vitrectomy not being performed but was not associated with age at surgery or IOL location. The risk of glaucoma development across all ages at surgery suggests a need for long-term monitoring.

Corneal power values for use with keratoprostheses and intraocular lenses

AbstractPurposeTo specify a keratoprosthesis (KPro) power value for use with an intraocular lens (IOL).MethodsRaytracing software was used to determine the imaging properties of both the natural cornea and conceptual KPro designs, and IOL power calculation methods were reviewed. Traditional calculations use ‘thick lens’ models for the overall eye, while also using ‘thin lens’ approximations for the cornea and IOL. The power of the natural cornea acts approximately at the apex, although this is unlikely to be the case for a KPro. The IOL location is determined using an empirical adjustment that is calculated from clinical results for natural eyes.ResultsThe use of a KPro has a similar optical effect to corneal refractive surgery, where the cornea no longer matches the original eye. A modification of the ‘double‐K’ calculation method can be used by specifying the KPro effective power at the original corneal apex, but still estimating the postoperative IOL location using the original corneal power. The KPro power is measured by assembling the KPro with fluid and a window to simulate the way it is used, recording the best focus power at room temperature with a 3 mm diameter aperture, rescaling to the in situ power at 35°C using refractive index changes, and then rescaling again to the power expected relative to the original corneal apex. When expressed as a K value, a keratometer refractive index of 1.332 is proposed. If necessary, clinical results may be used later to make empirical adjustments to the calculation method.ConclusionsA KPro power can be specified relative to the expected location of the original corneal apex using a keratometer index of 1.332. A double‐K calculation can then be used to determine the correct KPro and IOL power values for a pseudophakic eye.

Intraocular lens optic capture in pediatric cataract surgery.

Posterior capsule opacification (PCO) remains the most common complication of pediatric cataract surgery despite continuous efforts to reduce its incidence. For this reason, pediatric cataract surgeons have expended considerable effort into preventing and mitigating PCO. The intraocular lens (IOL) optic capture technique has been used for the prevention of PCO after pediatric cataract surgery for more than 20y, but there is still no professional consensus. However, recent research has shown encouraging results. The IOL optic capture technique can be performed without anterior vitrectomy to prevent PCO, even in younger children. The type and characteristics of IOLs used for optic capture technique, the location of IOL and the complications of IOL optic capture in children are here reviewed.

Observation on 25-gauge vitrectomy for the treatment of IOL-capsular tension rings dislocating

Objective To observe the clinical efficacy of 25-gauge vitrectomy for the treatment of IOL-capsular tension rings(CTR)dislocating into vitreous. Methods Seven eyes of 7 patients of IOL-CTR dislocating into vitreous were treated with 25-gauge vitrectomy.The capsular tension rings were removed through scleral tunnel incision, the surgeries of 5 eyes combined with suspension in ciliary sulcus. All cases were followed up for 3 months. The postoperative visual acuity and stability of the intraocular lens were observed. Results The last followed up time, the visual acuity were the same as preoperative one in 3 eyes.The location of intraocular lens of all cases were stable. Conclusion IOL- CTR dislocating into vitreous treated with 25-gauge vitrectomy is safe and effective. Key words: Len, intrcocular; Dislocation, capsular tension rings; Vitrectomy, 25-gauge

Intraocular lens ciliary sulcus suspension in aphakic vitrectomized eyes under anterior chamber perfusion

Objective To evaluate the clinical efficacy of suture fixation to ciliary sulcus of a foldable intraocular lens (IOL) with the 25 G anterior chamber perfusion in eyes that had pars plana vitrectomy combined with lensectomy. Methods This is a retrospective non-comparative study. The medical data of 31 eyes of 31 patients who had vitrectomy combined with lensectomy surgery for severe vitreoretin opathy from Jan, 2012 to Dec, 2013 were reviewed. The underlying vitreoretinal diseases were complicated ocular trauma(n=16), proliferative vitreoretinopathy (n = 8), proliferative diabetic retinopathy (n= 4), and lens dislocation in vitreous cavity (n=3). The uncorrected visual acuity (VA) of the 31 eyes was from LogMar 6.64 to LogMar 3.06 and the best corrected visual acuity (BCVA) was from LogMar 2.74 to LogMar 0.097. In addition, the preoperative aphakic period and stable posterior segment condition was maintained at least 6 months. All the surgical procedures were operated by one surgeon, and were that the foldable IOL was implanted and sutured to ciliary sulcus through 3 mm limbal incision under 25 G anterior chamber perfusion. The follow-up after the surgery was more than 3 months. The value of VA, BCVA, intraocular pressure (IOP), the number of corneal endothelium cells (NCEC), the condition of IOL location and complications in all patients were recorded. The statistical analysis was paired t test. Results The postoperative uncorrected VA reached from LogMar 3.32 to LogMar 0.097 that was better than the preoperative VA at 3 to 6 months after the surgery (P 0.01). The NCEC 3 months after the surgery was (1789±321)/ mm2 and compared with preoperative (1837±289)/mm2, the difference was not statistically significant (P>0.01). The IOL location was at the center in 29 eyes (93.54%), mildly eccentric in 1 eye (3.23%), and slightly tilt in 1 eye (3.23%). A transient vitreous hemorrhage occurred in 1 eye after the surgery. Conclusion Suture fixation to ciliary sulcus of a foldable intraocular lens (IOL) through 3.0 mm limbal incision with the 25 G anterior chamber perfusion for aphakic eye after vitrectomy combined with lensectomy is safe with stable IOP. Key words: Aphakic; Lens, artificial, foldable; Implantation; Anterior chamber perfusion, 25 G

Analysis of Purkinje images as an effective method for estimation of intraocular lens implant location in the eyeball

The implantation of an artificial intraocular lens (IOL) into a capsular bag in place of an extracted natural, but nontransparent lens is a standard therapy method in the case of cataract. Any decentration or tilt of the IOL can cause a deterioration of the retinal image quality, thus decreasing the vision quality. The analysis of the relative position of Purkinje images being a reflection of the point light source from the refracting surfaces of the eyeball determines the location of IOL inside the eye and thus enables to state its wrong or correct location. The paper describes the Purkinje experimental setup consisting of an illuminator (several infrared LEDs arranged in a circle), an imaging telecentric lens and image recording CCD camera and reports details of the system calibration The usefulness of the experimental setup has been proven both in laboratory conditions using artificial model of the eyeball and in measurements on human subjects. Simulations of the retinal image with different decentrations or tilts are shown.

Intraocular lens implantation for patients with coloboma of the iris.

The aim of this study was to analyze the techniques for intraocular lens (IOL) implantation in patients with coloboma of the iris. A retrospective cohort study was used to analyze the degree of iris coloboma and the characteristics of the crystalline lens in 56 patients with iris coloboma. The patients with a lesser degree of coloboma of the iris and an intact lens capsule were treated by iris suture and IOL implantation into the posterior chamber. Patients with an iris coloboma confined to one quadrant, severe iris atrophy and significant lens capsule coloboma were treated with an annular suture at the edge of the pupil and IOL implantation into the anterior chamber. Patients with a greater degree of iris coloboma and an intact lens capsule were treated with an artificial iris and IOL implantation. The patients were followed up for between five months and five years after surgery. Data relating to vision, photophobia, IOL location, postoperative complications and treatment were also obtained at follow-up. The vision of the patients was improved to varying degrees following the surgery, with the exception of those with amblyopia or serious corneal scars. The photophobia of the patients had also improved. The patients’ levels of satisfaction and comfort were deemed to be satisfactory. Early postoperative complications included hyphema, increased intraocular pressure and uveitis. However, serious complications such as corneal decompensation and IOL dislocation were not observed. Various techniques for IOL implantation were selected based on the degree of iris and lens capsule coloboma; these techniques were capable of improving the vision and photophobia of the patients.

Secondary intraocular lens interventions: predisposing factors, indications and coincident procedures

To evaluate the predisposing factors, indications and coincident procedures in patients requiring a secondary intraocular lens (IOL)-related intervention. We reviewed data on 183 consecutive secondary IOL-related procedures. Information collected included demographics, predisposing factors, IOL status, indication for surgery, coincident procedures, and final IOL location and fixation method. Of the 183 procedures performed, 73 were secondary IOL implantations, 68 were IOL exchanges and 42 were IOL repositionings. Predisposing factors were found in 88.6 % of the cases, the most common being complicated cataract surgery (39.8 %) followed by trauma (20.2 %). The most common indications for surgery in the anterior chamber IOL and posterior chamber IOL groups were pseudophakic bullous keratopathy ± failed graft (77.2 %) and subluxated IOL (57.53 %), respectively. A malpositioned or subluxated lens was found in 47.86 % of all pseudophakic eyes. A simultaneous procedure was performed in 67 % of cases, anterior vitrectomy being the most common (43.7 %), followed by keratoplasty (35 %). Secondary IOL-related interventions were associated with predisposing factors, complicated cataract surgery being the most common. Patients implanted with anterior chamber IOLs seemed to have a more complicated course requiring more complex secondary surgeries and associated procedures.

Clinical applications of ultrasound biomicroscopy in diagnosis and treatment of lens subluxation

To evaluate the clinical value in diagnosis and treatment of lens subluxation using ultrasound biomicroscopy (UBM). This study comprised 29 patients (32 eyes) that had cataract with subluxated lenses due to different causes admitted into our hospital between November 2000 and January 2002. All eyes received UBM examination preoperatively and postoperatively. Capsular tension ring (CTR) implantations were performed using different technique according to UBM examination. Then all patients received phacoemulsification and intraocular lens (IOL) implantation. The location of IOL and CTR and complications were evaluated postoperatively. Different kinds of subluxated lens shown different manifestations in UBM. The degree of zonular defect can be evaluated with UBM preoperatively. With UBM examination preoperatively, extent of lens subluxation less than 1/2 quadrant in 19 eyes while more than 1/2 quadrant in other 13 eyes were observed. Postoperative UBM examination in this series shown that CTRs were holding in place except one attached to the iris root. IOLs in 29 eyes were in proper position while IOLs in 3 patients were slightly tilted. The degree and extent of lens subluxation can be evaluated using UBM examinations preoperatively, which is necessary in the selection of surgical protocol. With postoperative UBM examinations, a precise observation on the actual location of CTR and IOL can be achieved to produce an objective evaluation of the surgical outcomes.