HOW TO CHOOSE A PRESCRIPTION SCUBA MASK

With many Optical Correction Choices Available, this guide is about helping you choose the right one for you.

Near-Sighted, Myopic or Negative Sphere Prescription           

Step Diopter lenses are stock lenses or pre made lenses available in .5 increments.

These lenses adjust only for the near - sighted  (Sphere) available –1.0 to –7.0 strengths.

Strengths  -7.5 to –10 usually are not stocked and take a couple of weeks for delivery.

These lenses are perfect for snorkeling featuring lower costs ($20 to $30) than custom ground lenses

Step Diopter lenses will not correct for cylinder or astigmatism

Fits only certain masks

Custom Lenses for Near - Sighted Rx

A custom lens mask is recommended if you have a cylinder reading greater than +1.0 or less than -1.0.  Using step diopter lenses on the higher astigmatism could cause migraine headaches.  Masks with custom lenses start at $159

Large selection of masks available

Far - Sighted, Presbyopia, or Positive Sphere Prescription
 

Step Diopter lenses are stock lenses or pre made lenses available in .5 increments.

These lenses adjust only for the far - sighted  (Sphere) available +1.0 to +4.0 strengths

These lenses are perfect for snorkeling featuring lower costs ($30 to $40) than custom ground lenses

Fits only certain masks

Custom Lenses for Far - Sighted RX

A custom lens mask is recommended if you have a cylinder reading greater than +1.0 or less than -1.0.  Using step diopter lenses on the higher astigmatism could cause migraine headaches.  Masks with custom lenses start at $159

Large selection of masks available

 
Bi-focal or Gauge reader RX

            Stock lenses are available for strengths of +1.0 to +3.0 in .5 increments with the bi-focal  lenses. The top (major part of lens is tempered glass and the bottom the gauge reader or bifocal.

Fits only certain masks

How to calculate your prescription or RX for a step diopter lens
 

 OD (Ocular Dexter) refers to your right eye.
 
OS (Ocular Sinister) refers to your left eye.
 
Sphere Refers to the degree of correction needed by your eye, measured in diopters. For nearsighted people this is always (-) negative.
 
Cylinder Refers to the amount of astigmatism in your eye (the degree by which your eye is not uniformly round).

Get your latest Rx from your optometrist

For the best result, you must add one half (1/2) of the cylinder number to the sphere number.

Take care to add or subtract correctly

Follow examples below to select RX

Example 1

                        Sphere   Cylinder   Axis

OD      -3.0                  .0            .0        
OS      -2.0                  .0            .0                 

RESULTS

RIGHT LENS –3.0   LEFT LENS –2.0

OD : Sphere of –3.0, plus ½ of the cylinder 0 : -3.0 + 0 = -3.0
OS :  Sphere of -2.0, plus ½ of the cylinder 0 : -2.0 + 0 = -2.0      

Example 2

                        Sphere   Cylinder   Axis

OD        -3.0         +.50            .0        
OS         -2.0          -.50             .0        

RESULTS

RIGHT LENS –3.0   LEFT LENS –1.5

OD : Sphere of –3.0, plus ½ of the cylinder +.50 : -3.0 + .25 = -3.25

CHOOSE 3.0

WATER NATURAL MAGINIFICATION WILL ALLOW USE ROUND DOWN

OS :  Sphere of -2.0, plus ½ of the cylinder -.50 :   -2.0 - .25  = -1.75

CHOOSE 1.5 

WATER NATURAL MAGINIFICATION WILL ALLOW USE ROUND DOWN

Example 3

                        Sphere   Cylinder   Axis

OD             -3.0         +.1.50         .0        
OS            -2.0          -1.50           .0        

RESULTS

CUSTOM

OD AND OS HAVE CYLINDER READING ABOVE +1.0 OR –1.0