Case Study: RM, a 41 y.o. amblyopic male was referred to my practice in 2006 from another optometrist. This optometrist felt it was better for the patient, and himself, if the patient sought care from another licensed eye-care provider. The patient was intent on wearing soft contact lenses. He was not interested in rigid contact lenses having previously experienced poor visual and comfort results. He presented wearing Hydrasoft custom toric contact lenses and stated that he was able to function adequately out of his right contact lens and had expected poor vision with his left amblyopic eye. However, the contact lens in the right eye needed to be replaced due to the patient losing it. The patient’s optometrist gave up after trying several lenses that were supposed to be the same previous right lens prescription. RM stated he could see reasonably well at times with the replaced right lenses but then the vision would always blur. He was a carpenter and was frustrated with his vision. He felt that his expectations were reasonable since he was able to see adequately and consistently with the original right contact lens prior to losing it. He felt the “good” lens was functionally stable.
His previous optometrist had ‘cut the cylinder’ in both eyes and prescribed a monovision system attempting to use the patient’s amblyopic left eye for near-point vision. He had prescribed the standard Hydrasoft toric design with a base curve of 8.6 and diameter of 14.2 for both eyes.
Presenting Hydrasoft Toric Soft Contact Lenses:
OD +5.75 -1.75 x 105/ base curve 8.6 mm./ diameter 14.2 mm.
OS +7.00 -3.00 x 065/ base curve 8.6 mm./ diameter 14.2 mm.
OD +5.50 -2.50 x 100 to 20/20- & J-2
OS +6.00 -3.50 x 068 to 20/60 & J-5
OD 44.25/42.50 @ 097
OS 45.50/42.25 @ 063
OD 43.84/42.00 @098
OS 43.71/41.40 @ 072
OD 11.8 mm.
OS 11.8 mm.
In 2006, I ordered the patient the SpecialEyes 59 Toric single vision trial soft contact lenses. I designed the base curve and diameter using the SpecialEyes Nomogram (developed by Rob Davis, OD and myself). This nomogram is intended to be used for average size corneas between 11.8 and 12.2 mm. I altered the power and created monovision by increasing plus power in the left amblyopic eye trying to utilize that eye for near vision
SpecialEyes 59 Custom Toric Contact Lenses:
OD +6.00 -2.75 x 100/ 8.3 mm. base curve/ 14.8 mm. diameter
OS +8.00 -4.00 x 068/ 8.2 mm. base curve/ 14.8 mm. diameter
Material: Hioxifilcon A 59%
The right lens was stable and achieved 20/20 acuity at distance and J5 at near. The left eye achieved 20/70 acuity at distance and J7 at near. Sphero-cylinder over-refraction found the right eye to be accurate and the left eye to be torqued slightly. A new left lens was ordered.
OS +7.00 -4.00 x 063/8.3 mm. base curve/14.8 mm. diameter
The patient was not benefitting from the additional plus on his left eye and was using the dominant right eye for reading. He used readers for near as needed.
He was satisfied with his vision, the visual stability, and the comfort of the SpecialEyes 59 Custom Toric single vision lenses. He continued to be seen annually and ordered a year supply of lenses.
Interestingly, the acuity of the left eye improved over the years. In March of this year his results were:
OD: +5.00 -2.00 x 092 20/20 +2.00 Add J-2
OS: +5.50 -3.50 x 066 20/30+ +2.00 Add J-3
OD: 43.01/41.91 @ 094
OS: 45.44/42.69 @ 052
OD: 11.7 mm.
OS: 11.7 mm.
Pupils: 4/2 OU (dim/bright)
Corneal topography, cell check, internal and external examination were all about the same.
He was interested in trying a multifocal or bifocal design to reduce his dependency on readers. Initially he only used the readers for extended reading or very small print. Now he needs readers for everything close.
The SpecialEyes 54 Multifocal, a custom aspheric design was ordered. The lenses were designed using the Arc Length Calculator that I developed. With the Arc Length Design, the diameter and base curve of the lens is based on the HVID (horizontal visible iris diameter) and corneal radius. The goal is a lens that will be 5.0 mm. larger than the cornea. Using this technique, each lens will rest 2.5 mm. outside the limbus no matter how large or small or how steep or flat the cornea is.
The Arc Length Design Calculator results were:
OD: 8.4 BC/ +5.30 -2.20 x 092/ +2.00 Add/ 14.8 mm diameter
OS: 8.3 BC/ +5.90 -3.80 x 066/ +2.00 Add/ 14.7 mm. diameter
Due to the small pupils, a small central near zone of 1.8 mm and a distance/peripheral zone of 4.0 mm were ordered.
The dispense visit and 2 week progress evaluation yielded excellent results.
OD Bright Illumination 20/20- & J-2 Dim Illumination 20/20-
OS Bright Illumination 20/50 & J-4 Dim Illumination 20/30-
The lenses centered and moved properly and draped the cornea with 2.5 mm. of coverage outside the limbus on both sides and in both eyes.
The patient rarely ever uses readers and is ecstatic with the results.
There are 3 important takeaways from this case. First, just because the patient has a difficult prescription and an amblyopic eye, this should not exclude us, as eye-care providers, from trying to help him. Also worth noting is that the Arc Length Design Calculator will increase the success of difficult prescriptions in sphero-cylinder designs. Secondly, now that SpecialEyes Custom Contact Lens Company offers both a custom aspheric multifocal design and a custom annular two-zone bifocal design, this increases the opportunity to help even more presbyopic patients with challenging prescriptions. Third, this amblyopic patient is an annuity to my practice, faithfully coming in every year for care and the ordering of all his lenses. The challenge may be in initially achieving success but then the following years typically result in ordering lenses similar in design.
**Enroll in the 54 Multifocal Email Course to learn how to fit and customize this design**
**For more information visit the 54 Multifocal Page**
P. Douglas Becherer, O.D., F.A.A.O.
Dr. Becherer is in private practice and is a consultant for Special Eyes Contact Lens Co. He developed the custom Arc Length Design technique. He holds patents for unique contact lens designs. He is past Chairman of the AOA Contact Lens & Cornea Section, Past President and OD of the Year for the Heart of America Contact Society. He is President of the Illinois State Board of Optometry. He is an Adjunct Professor for the University of Missouri and Adjunct faculty to Southern College of Optometry and Illinois College of Optometry. He has lectured and published extensively on the area of specialty contact lenses and corneal physiology.