GP Lens Case Grand Rounds Troubleshooting Guide – 17

Intermediate Presbyopia (New Wearer): Richard Baker, OD, MSEd

Background

Patient MM, age 43, is an art teacher who enjoys reading and drawing, roller skating, and exercising. She presented with symptoms which included not being happy wearing bifocal spectacles, difficulty with spectacle frame adjustments and very sensitive skin. She indicated she has always wanted to wear contact lenses.

Test Procedures, Fitting/Refitting, Design and Ordering

Case History:

Her medical history revealed allergies to foods and hypothyroidism. Her medications included thyroid replacement, aspirin and fiorinal for headaches. Her ocular history was unremarkable except for otc allergy eye drops used occasionally. Her visual history included spectacle lens wear since high school and attempted soft lens wear for six weeks a few years ago.

Slit Lamp Evaluation (without Contact Lenses):

Biomicroscopy testing revealed marginal blepharitis 1+, OU. Tear Break-up Time was greater than 12 seconds OU.

Manifest Refraction:

OD: -2.50 -1.75 x 175 20/20
OS: -2.50 -0.75 x 165 20/20
Add +1.25D, 20/20, OU

Anatomical Measurements:

Pupil Diameter: Mesopic: 4.5mm OU
Scotopic: 5.5mm OU
Corneal Diameter: 11.50mm OU
Palpebral Aperture: 9.80mm OU
Lower Lid: tangent to lower limbus of cornea
Dominant Eye: OD
Corneal Topography (sim Ks):
OD: 44.12 @ 178; 47.00 @ 088
OS: 43.50 @ 180; 46.12 @ 090

Consultation

A comprehensive discussion of patient expectations and review of lens designs related to patients prescription, anatomy and vision demands was completed at this point.The following options were considered:

  1. Single vision distance contact lenses in soft or GP material.
  2. Spectacles for mid to near range.
  3. Monovision contact lenses.
  4. Multifocal contact lenses.

Diagnostic lens evaluation revealed a GP design would provide best vision and performance. A translating design was also considered due the possibility of high amount of detailed near work. An aspheric design was utilized to treat the distance refractive error and provide adequate vision at mid and near range. The following lens parameters were ordered:

ODOS

Lens Design Essentials I Essentials I
Material Boston XO Boston XO
Base Curve Radius 7.50mm 7.40mm
Overall Diameter 9.50mm 9.50mm
Power -3.00D -3.50D

Initial Lens Dispensing

Upon dispensing, the following visual acuities were obtained:

Distance Vision OD, OS, & OU 20/20
Near Vision OD, OS, & OU 20/20

Slit Lamp Evaluation (with Contact Lenses):

Good centration with approximately 1mm lag with the blink and an alignment fluorescein pattern was present OU.

Patient Consultation and Education

A comprehensive training and orientation session was performed. Much time was spent educating patient about how to use the new multifocal design in her daily routines. Care was given to eye lid hygiene and dry eye issues including lid soaks and scrubs as well as how to use rewetting drops.

Follow-Up Care and Final Outcome

MM demonstrated good performance and satisfaction with the Essentials posterior aspheric multifocal design (Blanchard Contact Lens). It was necessary to move to the Essentials Series II – a higher effective add design – to achieve adequate reading comfort. PFAT at bedtime and in AM were needed to relieve dry eye symptoms. She was able to achieve 14 hours per day of comfortable lens wear without the use of spectacles.

Discussion and Management Options

The Essentials GP Multifocal is an aspheric translating design. It has a distance center and an aspheric back surface. The lens does not utilize any prism ballast or truncation. The lens is fitted similar to a single vision spherical base curve lens. The base curve radius is selected approximately 1D steeper than “K” but due to the posterior surface geometry, an alignment fluorescein pattern is often achieved. It can be manufactured in a medium or high Dk GP material. The Series (I, II, and III) designations allow for effective adds up to +2.25D. If insufficient add power is achieved, additional add power can be provided in paracentral annular form on the front surface (i.e., “CSA”).

A segmented translating lens design would have been another viable option. The advantage of this design would be a more defined near add and larger distance area allowing maximum distance vision. In this case, in my opinion, the patient could not tolerate the lack of intermediate vision and would have difficulty adapting to the lens thickness and truncation sensation caused by the lens.

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