Scleral Lens Design Research Articles

Medical Applications and Outcomes of Bitangential Scleral Lenses

To evaluate the clinical results of a new scleral lens design with a bitangential (nonrotationally symmetrical) periphery. All the necessary data were obtained during the 1-year study period. The bitangential scleral lenses were fitted and monitored according to a standardized fitting methodology. They were cut by precise submicron lathing from high-oxygen-permeable materials (including 10 scleral lenses from Menicon Z material). Subjective performance, visual acuity, and scleral lens-fitting characteristics were recorded after a median of 9.4 weeks (range, 3 weeks to 1 year). Diagnoses in the 213 eyes (in 144 patients) were keratoconus (n = 121 eyes; 56.8%), ocular surface diseases (n = 31 eyes; 14.6%), penetrating keratoplasty (n = 29 eyes; 13.6%), and other forms of irregular astigmatism (n = 28 eyes; 13.1%). Many patients (164 lenses; 77.0%) gave high ratings for comfort. The most common diameter was 20.0 mm (162 lenses; 76.1%) (range, 18.5 to 21.5 mm). Median decimal best-corrected visual acuity with the bitangential scleral lenses was 0.8 (equivalent to Snellen 20/25) (range, 0 to 1.5). Most bitangential scleral lenses showed good fitting characteristics: optimal values were seen for lens movement (208 lenses; 97.7%) and lens position (208 lenses; 97.7%). Median central corneal clearance was 0.2 mm; clearances differed in the four peripheral directions. The median stabilization axis was 140 degrees (range, 0 to 180 degrees) in the right eyes and 60 degrees (range, 0 to 180 degrees) in the left eyes. The bitangential scleral lens-fitting and performance characteristics were clear and effective for the health professional and the patient. The high-oxygen-permeable material Menicon Z may, in theory, be of benefit to corneas with a high oxygen demand.

Therapeutic use of mini-scleral lenses in a patient with Graves’ ophthalmopathy

Patients with Graves’ ophthalmopathy can be very challenging to manage secondary to the complex nature of their disease presentation. Patients may present with a variety of ocular findings including: lid retraction, periorbital and lid swelling, chemosis, conjunctival hyperemia, proptosis, optic neuropathy, restrictive myopathy, exposure keratopathy and/or keratoconjunctivitis sicca. Mini-scleral and scleral lens designs have been important in the management of irregular and regular corneas, and in the therapy of ocular surface diseases.We present here the case of a 48-year-old Caucasian male who had been diagnosed with Graves’ ophthalmopathy 13 years earlier. With significant ocular surface staining and over ten diopters of astigmatism, the patient had never been able to wear contact lenses comfortably. After being fit with the Mini-Scleral Design™ lenses, his vision improved to 20/25 OU, his ocular surface improved, and overall quality of vision increased.

Fitting an MSD (Mini Scleral Design) rigid contact lens in advanced keratoconus with INTACS

Keratoconus is a bilateral degenerative disease characterized by a non-inflammatory, progressive central corneal ectasia (typically asymmetric) and decreased vision. In its early stages it may be managed with spectacles and soft contact lenses but more commonly it is managed with rigid contact lenses. In advanced stages, when contact lenses can no longer be fit, have become intolerable, or corneal damage is severe, a penetrating keratoplasty is commonly performed. Alternative surgical techniques, such as the use of intra-stromal corneal ring segments (INTACS) have been developed to try and improve the fit of rigid contact lenses in keratoconic patients and avoid penetrating keratoplasties. This case report follows through the fitting of rigid contact lenses in an advanced keratoconic cornea after an INTACS procedure and discusses clinical findings, treatment options, and the use of mini-scleral and scleral lens designs as they relate to the challenges encountered in managing such a patient. Mini-scleral and scleral lenses are relatively easy to fit, and can be of benefit to many patients, including advanced keratoconic patients, post-INTAC patients and post-penetrating keratoplasty patients.

Update on scleral lenses

Scleral rigid gas-permeable lenses play an important and underappreciated role in the treatment of corneal disease. This review provides an update on scleral rigid gas-permeable lenses for the visual rehabilitation of ectasia and irregular astigmatism, and an update on scleral rigid gas-permeable lenses in the therapy of ocular surface disease. Several series and one case report present advances in the treatment of ocular surface disease with scleral rigid gas-permeable lenses. In addition, there are two reports describing one center's consecutive case experience using modern scleral lens design, predominantly in patients with ectasia and postkeratoplasty astigmatism. Finally, a comprehensive article reviewing the history and principles behind current scleral rigid gas-permeable lenses, with particular attention to the use of scleral rigid gas-permeable lenses in the management of ocular surface disorders was published. Clinicians who treat patients with ocular surface disease should be aware of scleral rigid gas-permeable lenses as a therapeutic option for their patients. Advances in lens design make scleral rigid gas-permeable lenses a practical option for an increasing number and variety of patients with corneal disease.

Modern Scleral Lenses Part II: Patient Satisfaction

To evaluate the subjective performance of modern scleral lenses in patients of the clinics of Visser Contact Lens Practice. In this cross-sectional survey, all the necessary data were collected at the first follow-up visit during the 5-month study period. In accordance with the preformed fitting technique developed at Visser Contact Lens Practice, four types of scleral lenses were used: spherical, front-surface toric, back-surface toric, and bitoric. Subjective performance was investigated during an interview that included the use of a five-point Likert scale and by means of a questionnaire supplemented by a 100-mm visual analog scale (VAS). The interview and questionnaire showed high scores for patient satisfaction with the current scleral lens in the 178 patients (284 eyes) (median score, 4; range Likert scale, 1-5; median score, >or=75; range VAS, 1-100). Significant increases in scores were seen with the current scleral lens compared to the former correction: 78.9% for comfort, 78.2% for visual quality, and 87.7% for overall satisfaction (n=284 eyes) (P<0.001). In the 99 eyes that switched from back-surface spherical to back-surface toric designs, the following significant increases were seen: 61.6%, 37.4%, and 65.7%, respectively (P<0.001). CONCLUSIONS.: High patient satisfaction was seen with all the modern scleral lens designs in the management of several forms of corneal abnormality. The interview showed differences in comfort, visual quality, and overall satisfaction in favor of the back-surface toric designs compared to the back-surface spherical designs.

Advantages of Toric Scleral Lenses

The purpose of this study was to investigate whether back surface toric scleral lenses stabilized (i.e., returned to their original position after rotation) and how long the return times were. Return time was studied in relation with actual wearing time and comfort; moreover, the performance of the spherical scleral lens was compared with the toric scleral lens design. Toric scleral lenses were rotated clockwise and counterclockwise over 60 degrees. Return times and the actual wearing time were recorded. Results were transformed into nasal and temporal return times for symmetry reasons. The present and former types of correction were compared for comfort (ranging from 0: very poor to 10: excellent) and regular wearing time. All the subjects attended regular follow-up visits. Forty-three subjects (43 lenses) entered the study. All the lenses returned to the original position within a median of 4 seconds after nasal rotation and 6 seconds after temporal rotation. A significant correlation was found between mean return times and actual wearing time (r = 0.63). Significant increases in median comfort (from 6-8) and median wearing time (from 15-16 hours) were demonstrated when the toric scleral lens designs were compared with the former type of correction (both p < 0.001). Median comfort and median wearing time also increased significantly after changing from spherical scleral lenses to the toric design (from 7-8 and from 14-16 hours, both p < 0.001, n = 27 eyes). Toric scleral lenses returned rapidly to their original position after rotation. The flattest meridian of the toric scleral lenses stabilized symmetrically. Patient interviews demonstrated differences in comfort and wearing time in favor of the toric design.

Medical Applications of Scleral Contact Lenses

The medical indications for, and outcome of scleral contact lens wear in 517 eyes of 343 patients attending a Scleral Contact Lens Clinic during a 5-year period from July 1988 to June 1993 were analysed. Keratoconus was the most common condition requiring scleral lens wear (36.2%), followed by aphakia (18.4%), postpenetrating keratoplasty (12.0%), irregular astigmatism secondary to corneal disease (12.0%), high myopia (12.8%), and ocular surface disorders (6.4%). The main indication was visual (85.8%), whereas therapeutic indications accounted for 8.2% of cases. Seventy-six percent of cases had previously failed with other types of contact lenses. The majority of patients were initially fitted with impression moulded polymethylmethacrylate (PMMA) lenses (90.5%); other scleral lens types included preformed PMMA lenses, preformed high Dk gas-permeable (GP) lenses, and a GP/PMMA hybrid scleral lens design. Initial scleral lens fitting was successful in 93.2% of cases, and 71% remained successful with a mean duration of 11.8 years' follow-up. Complications included corneal vascularisation (13.3% of eyes), episodes of corneal oedema (7.4%), corneal abrasion (3.1%), and giant papillary conjunctivitis (1.7%). In addition to 19 eyes initially fitted with GP lenses, there were 99 eyes initially wearing PMMA lenses that were subsequently refitted with GP scleral lenses.

Development of slotted scleral lenses

Brief Historical Introduction Advances in contact lens designs have largely provided tolerance levels greater than those achieved with the use of scleral lenses. However, scleral lenses remain the primary choice for a significant group of contact lens wearers. As most of this group consists of patients who are among the most dependent on contact lens wear, it is regrettable that so little energy has been directed to,yards the development of scleral lenses in recent years. Production of scleral lenses, with ensuing modifications and after-care has always been a time consuming and costly affair. The great majority of contact lens practitioners do not wish to burden themselves and their patients with the production and fitting of such appliances. As a result, the task of continuing scleral lens practice has fallen largely to the hospital ophthalmic departments and a few specialist practices which are fully equipped to cater for the particular difficulties. There is little doubt that this is the correct direction to move, particularly in view of the fact that scleral contact lens wearers nearly always have some underlying ocular pathology. In order to look at possible improvements to scleral lens design, it is necessary to consider how designs have already developed. Sabell (1981) I gave a comprehensive discussion of the history of scleral lenses. For the purposes of this article, it is relevant to mention the contribution of a few individuals. Eugene Fick (1888) 2 is accredited with the first attempts to put into practice the theoretical corneal neutralisation with fluid expounded upon by Leonardo da Vinci and Rene Descartes centuries earlier. Fick realised the potential of contact lenses in aphakia and keratoconus, two conditions for which correction with scleral lenses is sometimes indicated. Fick also recognised one of the principal complications of contact lens wear, namely, corneal clouding due to hypoxia. August Mfiller (1889) 3 also produced lenses principally for the correction of myopia. The first thirty years of the 20th Century saw little real progress made, with glass lenses being produced by Miiller of Weisbaden and Zeiss of Jena, but few contact lens wearers were able to achieve any satisfactory long term use. At the start of the 1920's W. Stock (1920) 4 attempted to use a four lens set to correct keratoconus. To cover the variations of the eye more comprehensively, such preformed fitting sets were extended, and inevitably became more expensive and cumbersome. The improvement in the understanding of corneal topography in the 1930's led to the realisation fhat reduction of pressure on the cornea would greatly improve ocular tolerance. The knowledge of optical principles dictated that the space between the front surface of the cornea and the back surface of the lens should be continually fluid filled to prevent impairment of the visual function. Josef Dallos emerged as one of the principal contributors in this time. Working on the assumption that the lacrimal fluid offered a good chance of achieving these ends he set about to conserve tears and allow for flesh tear interchange. He recognised that the success of scleral tens wear depended not so much on the accuracy of the scleral fit but on the adequacy of the fluid movement between the lens and cornea. From this, the technique of fitting with minimum corneal clearance was developed. Over the years he accumulated thousands of casts, and latterly favoured the use of 'type shells', selecting a near fit from an existing cast rather than carrying out an impression procedure every time. PMMA was developed in the late 1930's and was preferred by many contact lens workers to glass (Ruben 1975) 5 . Orbrig (Jenkin and Tyler-Jones 1969) 6 produced the first PMMA contact lens in the mid 1930's, and