Managing Irregular Astigmatism

Transcription

1 Non-scleral Lens Designs for Irregular Corneas Michael A. Ward, MMSc, FAAO, FCLSA Emory University Jessica Bezner Mannas, OD Koffler Vision Group Michael A Ward Potential COI Disclosures previous 12 months GPLI Advisory Board Columnist for Contact Lens Spectrum Review Board, Review of Cornea and Contact Lenses I do not own stock or have financial interest in any contact lens or lens care company GSLS 2016 Managing Irregular Astigmatism Irregular Astigmatism Causes and Indications for CL use Ectasias Keratoconus Pellucid marginal degeneration Post surgical RK/AK/Hex-K Lasik/Lasek/PRK Penetrating keratoplasty ICRS Scars Salzmann s Trauma Eyelid lesions OSD Keratoconus is the most common form of Irregular astigmatism The key to successful keratoconus management is choosing the appropriate form of visual correction for the individual patient Topographic Changes As keratoconus progresses, the superior cornea flattens as the inferior cornea steepens Page # 1

2 Contact Lens Corrective Options HEMA SCL / Si-Hy SCL Toric soft lenses Spherical SCL and spectacle combination Corneal GP : spherical, bitoric, reverse curve Piggyback SCL/GP Hybrid Scleral GPs Hydrogel options Standard soft/toric will work in early KC; at this stage glasses still work Thicker custom soft lenses may work in mild to moderate disease Early Keratoconus RGP Standard tri-curve Aspheric Myoflange helps to stabilize lens; superior alignment fit Typically 9.0 to 9.5mm diameter Post Refractive Surgery Topographic Categories Incisional RK, Hex-K, AK Ablative PRK, Lasik, Lasek, CK ICRS Indications for Contact Lens Management Objective Findings Irregular corneal topographies Irregular astigmatism Other: trapped debris, stromal haze,dlk,thin flaps, scars Irregular Astigmatism correction Irregular astigmatism cannot be adequately corrected with either spectacles or soft contact lenses. RGP lenses provide the best opportunity for visual rehabilitation in cases of irregular astigmatism. Ward MA; J Refract Surg 17;2001 Page # 2

3 Why Rigid Lenses work The rigid lens provides a smooth, regular anterior refractive surface for the eye, allowing tears to create an optical bridge by filling the space between the posterior lens surface and the anterior cornea. Corneal GP Lenses Set Realistic Expectations This is essential for new GP patients (previous SCL, new KC or post refractive) I tell patients that it will take 2-6 weeks to fully adapt; that it will feel like an eyelash in the eye initially feeling it every time they blink, but that will go away I liken it to the body s response to an unfamiliar odor When to use which GP Materials High Dk Ex: Menicon Z, Fluoro #151, Optimum Extreme, Boston XO Used primarily on compromised corneas and high power, large or thick lens designs EX: PPK, Refractive Sx, Fuchs, KC When to use which GP Materials Low to Mid-Dk materials EX: Fluoro #30, Boston ES, P-thin, Flourex #300 Used for increased dimensional stability when fitting toric designs and to improve surface wetting Corneal GP Lens Designs Spheric Bicurve Tricurve Multicurve Aspheric Fixed eccentricity Spherical oz / aspheric periphery Toric Front surface toric Bitoric Page # 3

4 Do you need a Front Surface Toric? Refract over best fit spherical GP lens If cyl is noted in over-refraction check K over CL If K readings are spherical (horizontal vertical), then residual cylinder present Resolve by ordering Front Surface Toric ; use lab consultant Do you have GP Lens Flexure? Refract over best fit spherical GP lens If cyl noted in over-refraction check K reading over CL If drum readings roughly match amount of cyl in over-refraction, then the GP lens is flexing on the eye. Resolve by altering design and/or increase lens thickness (CT) Standardize your Fluorescein application Place a drop of PFAT on the tip of a dye strip Apply to GP lens surface only Do not touch the lid or globe Visual Stability RGP lenses are used to favorably mold (splint) the cornea. This will stabilize topography and vision,and decrease astigmatism. SCL lenses will not stabilize topography or vision. RGP Fitting Post LASIK just the facts Choose initial BC 2 diopters steeper than mean post-op Ks Start with 10.5 diameter; larger to increase centration Use over-refraction for power determination Choose aspheric design with 0.17 edge lift (Star A ) Use fluorescein patterns as guide to finalize fit Use mid to high Dk material (e.g. Boston XO, XO 2,Optimum-X) Contact Lens Management after PRK / LASIK Summary GP Fluorescein patterns show apical clearance, mid-peripheral alignment and PC clearance Fit when refraction stable, 4-12 wk. SCL okay, but won t correct irregular astigmatism; GPs preferred Page # 4

5 Purpose Tandem SCL/GP (aka Piggyback) Lens Fitting To provide the corneal protective properties of a soft lens and the refractive benefits of a rigid lens A soft lens material is used to Protect from environmental debris and to minimize FBS from GP lens Provide shape support to nterior ocular surface Two Basic Methods of Piggyback Lens Fitting 1) Design GP lens to fit cornea, then dispense with SCL under GP 2) Place SCL on cornea, then fit GP to align with anterior SCL surface Soft (Base) Lens Options Silicone Hydrogel Materials approved for therapeutic use PureVision (Dk/t=110) Good O2, handling & reasonable draping Acuvue Oasys (Dk/t=147) Better O2; good handling & draping, 100%UVA & 96% UVB block A/O Night&Day (Dk/t=175) Highest O2; stiff, does not drape well; Biofinity (Dk/t=116) Good handling and draping Single -use (DD) SiHy is best option, but off-label Rigid Lens Options Menicon Z (Dk=189) Very High Dk 30d CW approval Boston XO (Dk=100), Boston XO 2 (Dk=141) Optimum Extreme (Dk=125 Tandem Acuvue Oasys as base Boston BXO Soper Design as top Page # 5

6 Contact Lens Care Recommendations Keratectasia For SCL/GP combined Tandem system: Remove GP, clean with GP daily cleaner, rinse and store in soft lens MPS Do not use Boston Cleaner on Menicon or other surface treated materials Remove SCL, clean, rinse and store in soft lens MPS In the morning, rinse & wet both lenses with soft lens MPS prior to placing on eye Do Not Allow GP Solutions to Come in Contact with SCL materials Ward, MA; CLSpectrum CL Correction over ICRS Intacs / PPLK Topography: Lasik-like periphery with KC-like center RGP needed to improve VA; SCL will not correct Fit large lenses with vault, or minimal pressure Piggyback often required Carefully monitor thickness of corneal tissue over ICRS Approximately 1,200,000 Radial Keratotomy cases performed in the US before ,000 cases performed in Canada Incisional Keratotomies RK, Hex-K, AK Increasing number of patients are returning for further correction due to progressive hyperopic shift Use RGPs for best VA Si-H for secondary option Avoid thick SCL due to propensity for vascularization along incisions Incisional Keratotomies RK, Hex-K, AK Large diameter RGP lenses required May use reverse curve (steeper secondary curve than base curve) Central pooling Pressure is on elbow; watch for staining Page # 6

7 Incisional Keratotomies RK, Hex-K, AK If patient had surgery years prior and has been happy until recent years, look for other causes of visual impairment If due to hyperopic shift (spherical), a simple Si-H SCL will probably work by returning pt to previous post RK correction Check for early cataract changes; even mild lenticular changes (PSC) can significantly impact visual quality in these patients due to potentially significant glare Custom Soft Lens Options Flexlens Novalens Kerasoft IC SPECIALTY SOFT LENS DESIGNS Intelliwave Custom Soft Contact Lenses Custom Soft Lens Parameters Base Curve Power Diameter Thickness Optic Zone Diameter Asphericity Reverse Curve Optic Zone Selection for Custom Soft Lens Applications Correction of Irregular Astigmatism Mark Andre and Matt Lampa This reflection will determine VA Page # 7

8 Case Reports Thank you! Page # 8