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Contact Lens Spectrum

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CLINICAL TIPS TO BOOST EFFICIENCY WITH SCLERAL LENS FITTING

Use these techniques to streamline the fitting process and to enhance your patients' scleral lens experience.

By: Daddi Fadel, DOptom
Contact Lens Spectrum February 1, 2022 Vol 37, Issue February 2022 Page(s): 34, 36, 51

To optimize the scleral lens fitting process, we must consider various factors including patients’ general health and ocular conditions, the different lens designs, and multiple factors involved in selecting an initial diagnostic lens. We must choose the diagnostic lens carefully, as this can have a significant impact on a patient’s experience as well as on the fitting process. Applying an inappropriate initial lens or trying more than one lens during the first visit may increase patients’ anxiety or cause them to view you as an inexperienced clinician. In addition, applying an inappropriate diagnostic lens can cause discomfort for patients and can complicate the fitting process.

Over time, as practitioners gain more confidence in fitting scleral lenses, they can develop efficiencies to optimize the fitting process. As a result, fitting scleral lenses becomes an enjoyable and emotional experience for both practitioners and patients. The following are the top five tips that I have developed to boost efficiency when fitting scleral lenses.

1) MAXIMIZE TECHNOLOGY

Optical coherence tomography (OCT) and ocular surface profilometry are important tools for reducing chair time. Ocular sagittal height, which must be estimated when selecting the first diagnostic lens, can be evaluated by examining the corneal profile or by using a corneal topographer, optical coherence tomographer, or a corneoscleral profiler.1 The lens periphery also must be selected and may be spherical, toric, asymmetric, or customized.

Corneoscleral profilers provide important information for initial lens selection, including ocular sagittal height, scleral toricity or asymmetry, and conjunctival irregularity. Based on the data collected, the software provides the parameters for the best lens fit, sagittal height, and peripheral toricity, reducing the number of lenses applied on the eye. When a scleral irregularity is observed (pinguecula, bleb, etc.), the software displays the parameters to communicate to the laboratory, including a localized vault or a notch (Figure 1). Ocular surface profilers also enable practitioners to empirically fit scleral lenses, reducing chair time and the number of reordered lenses.

Figure 1. Corneoscleral profiler showing ocular sagittal height and presence of scleral toricity or asymmetry. The software calculates the first lens sagittal height and lens toricity for a selected lens of a specific diameter. In this case, a pinguecula is also detected, and its depth, position, and width are shown.Image courtesy of Martin Conway.
Figure 1. Corneoscleral profiler showing ocular sagittal height and presence of scleral toricity or asymmetry. The software calculates the first lens sagittal height and lens toricity for a selected lens of a specific diameter. In this case, a pinguecula is also detected, and its depth, position, and width are shown.Image courtesy of Martin Conway.

2) CHOOSE A HIGHER SAGITTAL HEIGHT FOR THE FIRST DIAGNOSTIC LENS

When estimating the sagittal height of the first diagnostic lens, I recommend choosing the higher measurement. If the scleral lens touches the cornea, it is difficult to estimate how much it is touching. If the lens has a significant vault, however, it is easy to measure the clearance and to decrease it to the desired amount.2

3) EVALUATE SCLERAL LENSES FROM THE INSIDE OUT

Scleral lens assessments can be performed in one of two ways: from the outside in—starting in the scleral area and then moving toward the corneal area—or from the inside out.3 In my experience, the inside-out method, which involves starting the evaluation at the central area and proceeding toward the periphery, avoids unnecessary considerations and optimizes chair time.

For example, the scleral zone of a lens may appear flat or steep, prompting the practitioner to think that changes are needed in the periphery. When assessing the corneal area, however, the practitioner sees that the lens exhibits corneal touch or an excessive vault. Thus, the practitioner wasted time evaluating and considering changes to make in the periphery, when the lens applied is not the best one to assess. A lens with greater vault is needed in this case. Therefore, it’s essential to evaluate the lens in the center first and then in the periphery.

4) USE TORIC OR ASYMMETRIC DIAGNOSTIC LENSES

When advanced technology such as profilometry and OCT is not available, it is possible to evaluate scleral shape using a biomicroscope while a scleral lens is on the eye. To obtain input on the scleral profile, apply a spherical or a toric scleral lens and observe the clinical signs as well as the fluorescein or lissamine green dye patterns.4

In a study of prospective scleral lens patients, only 5.7% of eyes had spherical scleras, while 28.6% had toric scleras; scleras of the remaining 65.7% of eyes were asymmetric or irregular.5 When a diagnostic set that has asymmetric scleral lenses is available, I recommend selecting an asymmetric diagnostic lens. If only toric diagnostic lenses are available, begin the fitting process by applying a toric scleral lens. Make the desired changes to the lens based on the clinical signs and the dye patterns.

5) A SIMPLE TECHNIQUE TO ASSESS CLEARANCE THICKNESS

When using biomicroscopy to evaluate a lens fit, estimate the clearance thickness by comparing it to the known lens thickness. This evaluation is performed by rotating the slit beam by approximately 45º and using the optic section with white light. Experience is required for this evaluation, as practitioners need to be able to focus the light on the lens.

Conway recently proposed an innovative method to visualize the lens, particularly its anterior surface. He suggested wiping a fluorescein strip over the anterior surface of the lens. Once the patient blinks, the dye is distributed over the entire lens surface, allowing better visualization of the lens thickness (Figure 2).6 This technique helps reduce chair time as well as clinician frustration when assessing the lens fit.

Figure 2. Fluorescein facilitates observation of lens surfaces for evaluation of lens vault. (A) Anterior surface of the lens is not clearly visible. (B) Wipe the anterior surface with the fluorescein strip. (C) After blinking, the fluorescein stains the entire anterior surface, facilitating assessment. (A and C) Observation is performed with white light, rotating the slit beam by approximately 45°. In this case, the post-lens fluid reservoir was also stained with fluorescein before lens application.
Figure 2. Fluorescein facilitates observation of lens surfaces for evaluation of lens vault. (A) Anterior surface of the lens is not clearly visible. (B) Wipe the anterior surface with the fluorescein strip. (C) After blinking, the fluorescein stains the entire anterior surface, facilitating assessment. (A and C) Observation is performed with white light, rotating the slit beam by approximately 45°. In this case, the post-lens fluid reservoir was also stained with fluorescein before lens application. Image courtesy of Martin Conway.

MORE EFFICIENT = MORE ENJOYABLE

These tips help optimize chair time, and some prevent the need to apply multiple lenses on the eye, altering the fitting process. Clinical skill and efficiency can make the scleral lens fitting process more valuable, and this can improve patient perception of your expertise. This will enhance the patient experience and will transform the fitting process into an enjoyable moment for patients and clinicians. CLS

REFERENCES

  1. Fadel D. Taking the Mystery Out of Scleral Lenses: Patient Selection, Instrumentation, Fitting Techniques, and Follow-Up Evaluation. Contact Lens Spectrum. 2020 Jan;35:33-40.
  2. Fadel D, Barnett M. How to Customize Scleral Lenses. Scleral Lens Education Society. Webinar:2021. Available at https://www.youtube.com/watch?v=ea9v8i8iluw&t=1682s . Accessed Jan. 12, 2022.
  3. Johns LK, McMahon JA, Barnett M. Scleral Lens Evaluation. In Barnett M, Johns LK, eds. Contemporary Scleral Lenses, Theory and Application. Bentham eBooks:2017:201-241.
  4. Fadel D. Scleral Profile Assessment. Contact Lens Spectrum. 2019 Jan;34:40-42.
  5. DeNaeyer G, Sanders DR, van der Worp E, Jedlicka J, Michaud L, Morrison S. Qualitative Assessment of Scleral Shape Patterns Using a New Wide Field Ocular Surface Elevation Topographer: The SSSG Study. J Cont Lens Res Sci. 2017 Nov;1:12-22.
  6. Conway M. Assessing Scleral Lens Clearance. Contacts With Conway. Feb. 24, 2021. Available at https://www.youtube.com/watch?v=GD5QwZFlfoM . Accessed Jan. 13, 2022.

Dr. Fadel has a private practice in Italy where she designs and fits customized contact lenses. She is the editor-in-chief of the Journal of Contact Lens Research and Science. She has received lecture or authorship honoraria from AOS Software, Contamac, Eaglet Eye, Oculus, Soleko, and Wave Software.

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