NOTES, CASES, INSTRUMENTS DEVICES TO AID REFRACTION

GLEN F. HARDING, LIEUTENANT (MC), A.U.S.

Ogden, Utah

Many variations of single or multiple lens devices to aid refraction procedures have been produced and described. These consist basically of spherical, cylindric,

or cross cylindric lens or lenses mounted on shaft or handle arrangements.

Individual ophthalmologic refraction techniques provide many variations in re­fraction-aiding devices, regardless of whether the trial case or refractometer method is used. I have designed for my use the two refraction aids shown in fig­ure 1, the upper aid is spherical, the lower aid cylindric.

The spherical aid consists of a group of spherical lenses in quarter-diopter gradu­ations. The minus-power lenses are iden­tified by gold-plated rings, the plus-power lenses by nickle plating. Lens rings are 1 Yz inches in diameter, the lens power and sign are engraved on the periphery of each.

The spherical aid used chiefly for test­ing hyperopic eyes has the following ar­

rangement: a three-lens extension of + 0.25 (outer), +0.50, and +0.75 diop­ter; the single lens adjoining the plastic or tape-wound handle has a —0.25 diop­ter value.

The spherical aid used chiefly for test­ing myopic eyes has a corresponding lens arrangement of —0.25, —0.50, —0.75 in the three-lens extension, and + 0.25 diop­ter in the single ring.

Fig. 1 (Harding). Devices to aid refraction. A, upper, spherical refraction aid; lower, cylindri­cal refraction aid. B, Method of holding spherical refraction aid. Any one of the three exposed lenses can be used for trial case or refractometer procedures. C, By pivoting-finger movements, the spherical refraction aid will present a lens of opposite sign. D, Method of holding cylindric refraction aid. Either cylinder can be brought into a refractive position by a pivoting-finger move­ment. A rotary-finger movement changes the axis direction.

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408 NOTES, CASES, INSTRUMENTS

The spherical aid is so constructed as to pivot in the fingers (see figs. IB and 1C), thus readily presenting either minus and plus lens by a slight finger movement. This aid is used advantageously in build­ing up or reducing spherical power. The three-lens extension makes it easy to test the eye farthest from the refractionist without undue cramping. The one-half and three-quarter diopter lenses are use­ful in finding spherical strength, especial­ly in the case of patients who have poor perception and are unable to detect quarter-diopter differences.

The pair of graduated quarter-diopter spherical aids described are ample for average refractions. For amblyopic, aphakic, and high ametropic cases I use a pair of similar spherical aids having one-diopter graduations.

Figure 1 (lower) illustrates the cylin-dric refraction aid, with frosted areas for axis identification and oblique mounting as shown. A pivoting-circular motion with the fingers alternates either cylinder as desired, a rotary finger movement changes the axis direction (see fig. ID) . The aid used in average cases has a cyl-indric lens power of +0.25 and —0.25 diopter. For low acuity, a +0.50D. and —0.50D. combination is useful.

Refractive findings are considered com­plete in the average patient if further im­provement does not occur when checking with: (1) the +0.25D. and -0 .25D. lenses of the spherical aid. (2) The + 0.25D. and -0.25D. lenses of the cyl-indric aid when held, (a) parallel with the axis of the patient's cylinder; (b) crossed with the axis of the patient's cylinder; (c) if the patient's final correc­tion is spherical only, the cylindric aid's lenses have been held at two or more meridians. All this takes but a moment with the rapid use of the two refraction aids. These changes are easily understood by the patient, yet the lens repetition is

ample, without fatigue to the patient, in the elimination of any practical error.

The dexterity of the system eliminates the need of fogging on most patients not ordinarily refracted under cycloplegic, also prevents overcorrection on manifests and postcycloplegics. The shifting of many lenses in trial frame and refractometer is lessened, necessitating fewer accommo­dative changes and diminishing fatigue for the patient.

Station Hospital # 2 , Fort Huachuca, Arizona.

REFRACTION CLINIC*

DISCUSSION BY ALBERT E. SLOANE, M.D.t

Boston A bookkeeper, aged 24 years, had been

refracted with and without drops and giv­en glasses two months ago. He finds that he sees much better at near with these glasses but must remove them after a short while. The discomfort cannot be described specifically, but a definite sense of relief is obtained when the glasses are removed, although the vision becomes blurred. He states that near vision is most uncomfortable with and without the glasses.

He is now wearing: O.D. +3.25D. sphere; O.S. +3.25D. sphere.

Examination: Vision in each eye was 20/40; with a +3.00D. sphere it was 20/20.

P.P. (convergence) = 12 cm; amp. ace. 9 diopters, both eyes; adduction: 16Δ; abduction: 8Δ.

Induced phorias (with glasses)—dis­tance : 8Δ exophoria ; near : 12Δ exophoria.

Habitual phorias (without glasses)— distance: 4Δ exophoria; near: 8Δ exo­phoria.

* From the House Officers' Teaching Clinic, Massachusetts Eye and Ear Infirmary.

t Director of Department of Refraction.