GP lens eye Rounds

Inferior Decentration Case

Allison Jussel Zagst OD, MS, FAAO

History

• HPI: 45 year-old white female with a history of inadequate vision, multiple Rx checks, and acne rosacea. The patient did not wear glasses until her early 40’s but felt that her vision was degrading. She currently wears progressive lenses.
• CC: Blurry vision at distance and near. She stated that she can “see” but her vision is not as “crisp” as she would like. She also noted that there is often the “memory of an image” around an image. She was interested in contact lenses.
• Modifying factors: Patient is currently taking Accutane.

Examination

• Entering visual acuities:

• Refraction:

OD -0.25 -0.50 x 070, 20/20
OS -0.25 -0.25 x 105, 20/20
ADD: +1.50D

• Slit Lamp Examination:

• Corneal Topography (Figure 1):

Keratometry: 42.67D/43.43D 42.79D/43.28D
HVID: 12 mm

• Dilated Fundus Examination: Retina is intact with no holes or tears

Decision Making Process

Patient was consulted on all contact lens options: soft, corneal GP, and scleral lenses as well as the option of continuing in glasses. The patient was interested in GP contact lenses to provide the best possible visual acuity. Scleral lenses were suggested as an option to also address her dry eye , likely worsened by Accutane; however, the patient was apprehensive about the price and wanted to start with GP lenses and consider scleral lenses in the future. Higher order aberrations and dry eye were also discussed as further causes of degraded vision.

Fitting and Evaluation

• Diagnostic fitting
  • Lenses selected from diagnostic fitting set based on corneal topographies:

OD: Base Curve Radius (BCR): 7.85mm; Overall Diameter (OAD): 9.3mm; Power: -2.00DS, ORx: +1.25 -0.25 x 084
OS: Base Curve Radius (BCR): 7.76mm, Overall Diameter (OAD): 9.3 mm, Power: -2.00DS, ORx: +0.75 -0.50 x 119

• • Both lenses fit mildly steep w/ mild dimple veiling, were inferiorly decentered with poor lid attachment, and had good edge lift 360˚
  • Plan: Increase overall diameter (OAD) to 9.6 mm to increase lid attachment and include spherical equivalent over-refraction.
• First dispense
  • Lenses dispensed OU

OD: 20/20 ORx: Plano
OS: 20/25 ORx: +0.50DS 20/20

• • Both lenses were better centered, demonstrated an alignment fit, and showed adequate movement
  • Plan: Trial lenses for one week and return to the clinic for a follow-up visit.
• First follow-up visit
  • Patient noted blurry vision at distance, especially while driving at night and discomfort with lenses.
  • Lenses on eye:

OD: 20/20- ORx: +0.25DS 20/20
OS: 20/20- ORx: +0.50DS 20/20
OU: 20/20

• • Lens-to-cornea fitting relationship:

OD: Mild pooling centrally, mild inferior decentration, and poor lid attachment
OS: Mild inferior nasal decentration

• • Plan: Increase lens diameter to 9.8mm OU, flatten BCR OD by 0.50D, include over-refraction OU
• Second dispense
  • Lenses dispensed OU

OD: 20/20-3
OS: 20/20-2
OU: 20/20

• • Lenses were better lid attached, centered well, and had an alignment fitting
  • Plan: Wear lenses for one week and return to the clinic wearing lenses.
• Second follow-up visit
  • Patient returned with some slight discomfort wearing the lenses and noted difficulty with night driving
  • Over-refraction over lenses

OD: +0.25 -0.75 x 083
OS: +0.50 -0.75 x 117

• • Plan: Order lenses with over-refraction and increase diameter to facilitate improved comfort
• Third dispense
  • Lens Parameters:

OD: BCR: 7.85mm; OAD: 10.0mm; Power: -0.62 -0.75 x 083
OS: BCR: 7.67mm; OAD: 10.0mm; Power: -1.00 -0.75 x 117

• • Visual acuity

OD: 20/20, ORx: PL
OS: 20/20, ORx: PL

• • Lenses were lid attached, centered well, had good movement, and an alignment NaFl pattern
  • Plan: Finalize lenses. Patient reported improved vision and comfort with new lenses.

Clinical Pearls

• A larger OAD is helpful in aiding in a lid attached fit
• A flat lens may decenter so centering the lens with your finger and assessing fluorescein pattern is a useful evaluation tool!