Endothelial physiology and intraocular lens implantation

Intraocular lens complications requiring removal or exchange

Intraocular lens (IOL)-related complications are caused primarily by mechanical trauma, inflammatory or infectious complications, or optical problems. Complications may occur at the time of surgery or be the result of an ongoing postoperative process. Mechanical and inflammatory injury may produce corneal decompensation, cystoid macular edema, hyphema, uveitis, and glaucoma, causing reduced vision and in some cases chronic pain. Optical problems may be due to a wrong power of the IOL or to postoperative decentration or dislocation of the lens. Ophthalmologists should be aware of the indications for IOL removal or exchange in those patients who have ongoing IOL-induced injury or impairment. Removal or exchange of an IOL frequently involves a complex decision-making process and is often associated with immense technical challenge. Various medical and surgical treatments may be tried to correct IOL problems before the decision is made to remove or exchange the lens.

Experimental evaluation of a phakic anterior chamber implant in a primate model. Part II. Pathology

Anterior chamber intraocular lenses were implanted in 50 phakic primate eyes and followed by serial histopathology for two years. Significant observations included corneal endothelial alterations, haptic erosion into and encapsulation by peripheral iris and ciliary body, and chronic low grade inflammation.

Fellow eyes in aphakic and pseudophakic bullous keratopathy

We studied the contralateral eye of ten consecutive patients in whom corneal decompensation had occurred following cataract extraction to detect the beginnings of any corneal disease in that eye. Patients with a previous history of surgery, trauma, or ocular disease were excluded. In the study group, the mean endothelial cell count was 1,852 cells/mm2 and the central corneal thickness was 0.572 mm. A comparable group of control eyes with cataracts demonstrated a mean endothelial cell count of 2,446 cells/mm2 and central pachymetry of 0.514 mm. Patients with corneal edema following cataract extraction should be carefully evaluated for the presence of endothelial dysfunction in the opposite eye.

Complications of prosthetic intraocular lens implantation: a histopathological study

A total of 104 eyes and 43 resected corneal discs from patients with failed intraocular lens implants (IOL) received over a period of 35 years were subjected to histopathological analysis. Eyes collected at necropsy from 18 people with clinically successful implants were also examined. Corneal decompensation leading to bullous keratopathy was the most frequent reason for failure, followed by glaucoma and intraocular inflammation. Of 18 cases in which inflammation was the principal clinical cause of failure 12 presented as infectious endophthalmitis, but minor degrees of sterile uveitis were fairly common. Retinal detachment was seen in seven cases. The interval between IOL implantation and the onset of serious complications varied from one month to 29 years, indicating that the presence of prosthesis will always entail a latent risk of an adverse tissue response, albeit slight.

Complications of intraocular lenses. A historical and histopathological review

Recent improvements in intraocular lens (IOL) design, manufacturing techniques, and surgical techniques have greatly reduced the incidence of complications following implantation, and many authors now consider IOL implantation to be among the most safe and effective major surgical procedures. However, adverse reactions are still seen--some as late sequelae of earlier IOL designs and implantation techniques and some as sequelae of more recent implantations using "state-of-the-art" lenses and surgical techniques. Complications may be due to various factors, including surgical technique, IOL design, or the inability of some eyes with preexisting disease to tolerate an implant. The authors trace the evolution of IOLs since Ridley's first implant, summarizing the modifications in lenses and surgical techniques that were made as complications were recognized. They then review the clinical and histopathological features of selected cases from more than 200 IOLs and/or globes removed due to IOL-related complications and studied in the University of Utah Ocular Pathology Laboratory. It is hoped that this review will provide insights into the pathogenesis of IOL complications, enhancing the current success of implant procedures and stimulating further basic and clinical research in this area.