David P. Piñero, PhD
Full scleral lenses are contact lenses that rest entirely on the sclera, with no bearing or touch on the corneal surface or limbus.1 This type of lens typically has been considered as an appropriate option for the correction of irregular astigmatism (post-LASIK irregularity, post-keratoplasty, keratoconus), which is neutralized by the tear meniscus formed between the cornea and the contact lens.2 Likewise, the level of wearing comfort with these lenses is high as they only rest on the conjunctiva, which has lower sensitivity than the cornea and minimizes the interaction with the eyelid.2 This case report shows the clinical outcome obtained with a full scleral contact lens (ICD 16.5, Paragon Vision Sciences, distributed by Lenticon, Madrid, Spain) in a cornea with high levels of astigmatism and corneal irregularity after radial keratotomy and several retreatments using different corneal refractive surgery techniques.
A 47-year-old man visited our Contactology Unit of the Ophthalmology Department (Oftalmar) of the Vithas Medimar International Hospital in Alicante in January 2015 with a medical report of all of his previous ocular surgical procedures and treatments. The patient underwent a bilateral radial keratotomy (RK) procedure several years ago for the correction of -2.00 D of myopia in both eyes.
Due to an unsuccessful outcome, the patient underwent several retreatments in both eyes, including transverse and arcuate keratotomies as well as photorefractive keratectomy (PRK). The final visual result was very unsatisfactory, with manifest refraction of +6.00 -6.00 x 20º and +8.00 -6.00 x 40º in the right and left eyes, respectively.
The corrected distance visual acuity (CDVA) was poor, with decimal values of 0.4 and 0.5 in the right and left eyes, respectively. Likewise, the corrected near visual acuity (CNVA) was very limited in both eyes (J8 and J3 in the right and left eyes, respectively, addition +1.75 D). After performing some trials with different contact lens designs (only tolerated for 3 or 4 hours), he came to our clinic asking for a new design that would increase the wearing time and provide good visual acuity.
Figure 1. Slit lamp appearance of both corneas.
On slit lamp examination, the cornea showed several leukomas (Figure 1). A complete evaluation of the corneal structure was performed with the Scheimpflug photography-based system Sirius (CSO, Firenze, Italy). Figures 2 and 3 show the corneal thickness map, tangential map of the anterior corneal surface, and elevation maps of the anterior and posterior corneal surfaces of the right and left eyes, respectively
A very irregular topographic pattern with significant variability of corneal power in the central area was observed in both eyes. Mean central corneal thickness was 528 and 548 µm in the right and left eyes, respectively. Mean right and left eye keratometric readings were 30.20/41.78/27º and 30.48/47.68/25º, respectively.
Figure 2. Evaluation of the corneal structure of the right eye by means of the Scheimpflug photography-based system Sirius (CSO, Firenze, Italy). Top left: Corneal thickness map. Top right: Anterior tangential topographic map. Bottom left: Elevation anterior topographic map. Bottom right: Elevation posterior topographic map.
Figure 3. Evaluation of the corneal structure of the left eye by means of the Scheimpflug photography-based system Sirius (CSO, Firenze, Italy). Top left: Corneal thickness map. Top right: Anterior tangential topographic map. Bottom left: Elevation anterior topographic map. Bottom right: Elevation posterior topographic map.
Scleral Lens Fitting
Due to the high level of irregularity, a full scleral contact lens that rested only on the sclera was fitted. Specifically, the ICD 16.5 (Irregular Corneal Design) contact lens (Paragon Vision Sciences, distributed by Lenticon, Madrid, Spain), which has four differentiated zones allowing correct centration with no corneal touch. These zones are: central clearance zone (CCZ), peripheral central clearance zone (PCCZ), limbal clearance zone (LCZ), and scleral landing zone (SLZ) (Figure 4). This contact lens is fitted based on the sagittal height rather than keratometry.3 It is a rigid gas permeable (RGP) contact lens manufactured in Paragon HDS 100 material (Paflufocon D) from Paragon Vision Sciences (USA). This material is a thermoset fluorosilicone acrylate copolymer derived primarily from siloxane acrylate, trifluoroethyl methacrylate and methylmethacrylate, with a water content of less than 1% and a Dk (oxygen permeability) of 100 Fatt units.
Figure 4. Diagram showing the design of the contact lens fitted in the current case report.
According to the manufacturer, a central apical clearance between 300 and 400 µm must be present for an adequate fit. In our case, after several tries, the most comfortable and stable fit was achieved with the following parameters:
-Right eye: sagittal height (SAG) 4600 µm, optical power of -11.25 D, SLZ -2.
-Left eye: SAG 4500 µm, optical power of -12.25 D, SLZ -4.
These lenses provided an apical clearance of 443 and 447 µm, respectively, as measured by spectral-domain optical coherence tomography (DRI OCT Triton system, Topcon). The contact lens was well-centered with an appropriate scleral landing. The decimal distance visual acuities with the contact lens were 0.8 and 0.4 in the right and left eyes, respectively. At near, visual acuities of J3 and J5 were achieved without correction, respectively. At 6 months, the patient presented at our clinic with complaints of blurred vision. Decimal distance visual acuities with the contact lens were 0.6 and 0.4 in the right and left eyes, respectively. With overrefraction of +1.00 -1.50 x 120º and +1.50 -1.75 x 165º, the decimal visual acuity improved to 0.8 and 0.6. In the topographic analysis, we observed a flattening effect in both corneas (Figures 5 and 6). It should be noted that these types of corneas with radial incisions are significantly weakened, with altered biomechanical properties. In this case, the tear meniscus and the lens had induced some level of corneal reshaping, although this was not the intention.
Figure 5. Evaluation of the changes in the corneal profile of the right eye by means of the Scheimpflug photography-based system Sirius (CSO, Firenze, Italy). Top left: Sagittal map pre-fitting. Top right: Sagittal map after 12 months of contact lens wear. Bottom: Diffference map.
Figure 6. Evaluation of the changes in the corneal profile of the left eye by means of the Scheimpflug photography-based system Sirius (CSO, Firenze, Italy). Top left: Sagittal map pre-fitting. Top right: Sagittal map after 12 months of contact lens wear. Bottom: Diffference map.
We performed a refitting of the same contact lens with the following parameters:
-Right eye: SAG 4500 µm, optical power of -12.25 D, SLZ -4.
-Left eye: SAG 4500 µm, optical power of -12.00 -3.25 x 175º, LCZ Steep +5.00.
In the left eye, the use of a toric contact lens was necessary to achieve a satisfactory level of visual acuity. With the refitting, the patient achieved decimal visual acuities of 1.0 and 0.6 in right and left eyes, respectively. The final apical clearance in the right and left eyes was 350 and 406 µm. This outcome has been maintained for one-and-a-half years.
Figure 7. Visualization of the apical clearance by means of spectral-domain optical coherence tomography of the final scleral contact lens fitted. Top: right eye. Bottom: left eye.
This case report shows the clear applicability of the new designs of full scleral contact lenses in corneas with high levels of irregularity. Specifically, we show the application of this type of contact lens for achieving a complete visual rehabilitation in an eye with high levels of astigmatism and irregularity after corneal refractive surgery. These lenses are able to provide a significant increase in visual acuity combined with a significant improvement in visual quality while maintaining high levels of comfort. A contact lens refitting may be necessary in corneas that are biomechanically altered, such as those with previous incisional procedures, as some level of reshaping may be induced in the initial period of wearing.
More studies are necessary in the future to evaluate the results of the scleral lens evaluated in the long-term, including the analysis of other variables, such as corneal endothelial cell density, patient satisfaction evaluated with a validated questionnaire or the level of contrast sensitivity achieved.
1. Van der Worp E, Bornman D, Ferreira DL, Faria-Ribeiro M, Garcia-Porta N, González-Meijome JM. Modern scleral contact lenses: A review. Cont Lens Anterior Eye 2014; 37: 240-50.
2. Pullum KW, Whiting MA, Buckley RJ. Scleral contact lenses: the expanding role. Cornea 2005; 24: 269-77.
3. Piñero DP. Fitting of a new design of full scleral contact lens in advanced keratoconus with previous implantation of intracorneal ring segments. Int J Kerat Ect Cor Dis 2015; 4: 56-9.
David has a degree in Optics and Optometry (University of Alicante, 1998) and a degree in Documentation Science (University Oberta of Catalunya, 2006). He received his PhD from the University of Alicante in 2010 with the defense of the doctoral thesis entitled “Characterization and modeling of the effect of intrastromal ring segments in ectatic corneas.” Furthermore, he obtained the title of University Specialist in Pre- and Post-Surgical Optometry by the University of Valladolid in 2001.
His clinical activity is currently developed at the Department of Ophthalmology (OFTALMAR) of the Vithas Medimar International Hospital (Alicante, Spainn). He has published more than 150 papers in peer-reviewed journals, most of them in the area of cornea, and participated in the elaboration of 20 book chapters. He is also currently a researcher and lecturer at the Department of Optics, Pharmacology and Anatomy of the University of Alicante, and Associate Editor of Journal of Optometry, BMC Ophthalmology and Journal of Ophthalmology.