GP lens eye Rounds

OCULAR SURFACE DISEASE: Troubleshooting Foggy Vision Case

Rob Ensley OD, FAAO, FSLS

History

• 42-year-old Caucasian female s/p PKP x 2 OU secondary to advanced keratoconus.
  • OD: 1998, 2020
  • OS: 2007, 2013
  • Prednisolone acetate 1% QD OU
• Previously tried scleral lenses just over one year ago but struggled with application.
• Best corrected VA in spectacles was 20/50 OD and 20/400 OS.
• Failed with corneal GP lenses. Desires to re-try scleral lenses.

Decision-Making Process/Fitting and Evaluation

• Scleral Fit
  • OD: 18.0 mm OAD, achieves 20/20 with front surface toric optics.
  • OS: 18.5 mm OAD, achieves 20/20 with spherical optics.
  • Unique pH and LacriPure cleaning/storage and application solution regimen.
  • Uses See-Green Scleral Lens Inserter stand to help with application; can do with ease now.
• 1-month scleral follow-up post dispense
  • Chief complaint of cloudy vision left eye after several hours of wear. She denied any significant comfort issues and her eye appeared white and quiet outside of the slit lamp.
  • Excessive tear exchange noted in the superior quadrant resulting in midday fogging (MDF). (Figure 1)

Figure 1: Excessive fluid reservoir clearance in the superior quadrant as observed with he slit lamp (left) and the AS- OCT (right)

• • No surface wetting issues or deposits.
•  Management
  • Steepened peripheral curve along the superior quadrant.

Clinical Pearls

Foggy vision can be the result of the relationship between the tear film and the anterior lens surface (poor surface wetting) or post-lens tear debris (midday fogging or MDF). Typically, vision is clear upon initial application, but described as becoming foggy or cloudy as wear time increases. A comprehensive case history and evaluation of the scleral lens on eye can help differentiate between these two clinical entities.

Case History Considerations

• Vision
  • Poor lens wettability can occur any time, even within minutes. The foggy vision will be transient, and blinking may clear the vision temporarily.
  • MDF will often occur gradually after hours of wear, although the more misaligned the peripheral curves are to the sclera, the earlier MDF will occur. Once vision is foggy, it remains consistently foggy. Blinking does not significantly help.
• Comfort
  • Dry eye-related symptoms while wearing scleral lenses should be carefully evaluated. If the tear film interacts poorly with the anterior surface of the lens, symptoms may include a non-distinct, diffuse grittiness or a stickiness while blinking. A sensation of dryness can also result from the interaction between the posterior eyelid, tear film, and anterior lid surface.
  • Haptic alignment does not need to be perfect to yield good comfort. If vision is foggy, but the patient denies significant comfort concerns, the cause can still be either poor anterior surface wetting or MDF. Evaluation with the slit lamp biomicroscope may be required to confirm the cause. However, patients may also often show where the lens is uncomfortable. In those quadrants or meridians there will typically be discernible edge lift or blanching and impingement. Significant edge lift is more likely to lead to MDF.
• Scleral Lens Care
  • Improper or inadequate lens care is more likely to contribute to increased deposition or poor wettability of the scleral lens surface. Review solutions that are being used for cleaning, storage, rinsing and application, as well as other cosmetic and hygiene products that the patient is using on their face or hands while applying or removing lenses.

Scleral Lens Evaluation

• Poor surface wetting
  • Can be observed with white light and low magnification.
  • Clinical appearance
  • Lipid or protein deposition on the front surface.
  • Condensation-like effect that forms typically from inferior lens upwards post-blink.
  • Dry spots with bead-like pooling of the tear film adjacent to the dry spots.
• Midday Fogging (MDF)
  • A non-transparent, murky tear layer that is visible between the posterior lens and anterior corneal surface.
    • Appreciable in the slit lamp and via OCT.
  • Careful evaluation of the scleral fit, particularly the limbal clearance and haptic alignment, can determine where the lens fit may be too loose, allowing for excessive tear exchange, or too tight, increasing mucus production.
    • The use of vital dyes to paint over the scleral lens on the eye can help the practitioner visualize where the influx of tear exchange is.

Overall Clinical Pearls: Mid-Day Fogging

• Tear film components including epithelial cells, granulocytes, inflammatory proteins, and non-polar lipids build up between the posterior surface of the lens and the anterior corneal surface.^1,2
• According to the SCOPE study, 26.1% of scleral lens patients reported MDF.³
• Studied theories for MDF at times yielding contradictory results
  • Misalignment of lens haptics (loose fit) facilitates tear exchange and entrapment of tear lens debris.⁴
  • Tight edges and excessive corneal clearance may contribute to MDF.⁵
  • Inflammation is a contributing factor, given greater amounts of inflammatory particulates in the tear film.⁵
• Troubleshooting
  • Improve fit
    • Improve haptic alignment
    • Reduce corneal clearance
  • Review application technique
    • Wide apertures – avoid interaction with eyelids and lashes
    • Avoid significant pressure on lens application – less suction
    • Review filling solution – consider buffered solution
    • Add a viscous non-preserved artificial tear to the lens bowl
  • Manage ocular surface disease (OSD) and eyelid hygiene
  • Remove lens and rinse as needed

Sources

1. Postnikoff CK, Pucker AD, Laurent J, Huisingh C, McGwin G, Nichols JJ. Identification of leukocytes associated with midday fogging in the post-lens tear film of scleral contact lens wearers. Invest Ophthalmol Vis Sci 2019;60(1):226–233.
2. Walker MK, Bailey LS, Basso KB, Redfern RR. Nonpolar lipids contribute to midday fogging during scleral lens wear. Invest Ophthalmol Vis Sci 2023;64(1):7.
3. Schornack MM, Fogt J, Harthan J, et al. Factors associated with patient-reported midday fogging in established scleral lens wearers. Cont Lens Anterior Eye 2020 Dec;43:602-608.
4. McKinney A, Miller W, Leach N, et al. The cause of midday visual fogging in scleral gas permeable lens wearers. Invest Ophthalmol Vis Sci 2013;54(15):5483.
5. Fogt JS. Midday Fogging of Scleral Contact Lenses: Current Perspectives. Clin Optom (Auckl) 2021 Jul;13:209-219.