The best fitting contact lenses i've tried were 8.5 basecurve and 14.5 diameter. Ones with an 8.6 basecurve and the same diameter seemed to slip around.. Now i'm meant to be trialing ones with an 8.7 basecurve, and a 14mm diameter. So, as the 8.6's were such a bad fit, should i expect these to be even worse, or will the smaller diameter size mean they are a better fit? (My optician says shes not worried about the sizes so much.. but i want to get an idea of how they might fit my eyes)
2007-09-07 10:17:37 · 4 answers · asked by Libra ♎ 4 in Health ➔ Optical
8.50/14.5 does give some information, compared to a different specification *of the same lens design from the same manufacturer* but otherwise it's a bare shorthand, little more, with modern lenses. Almost equivalent to a shoe size, and (just like shoes) other elements of the design can lead to a very different fit.
One 8.5 may not fit the same as an 8.5 from another manufacturer, due to different central optical diameter, peripheral curves (or asphericity), thickness or the relative rigidity of the material...
Everything else being equal, yes, you're right, a 8.7 / 14.00 would be a looser fit than a 8.50 /14.50. But there are lots of other parameters unstated which could sway the result.
If your optician wants to try a change for any reason: better oxygen supply, durability, easier cleaning... a trial pair should be worth the attempt, but be prepared to report if they're not doing what you want/like.
2007-09-07 11:35:22 · answer #1 · answered by Pedestal 42 7 · 2⤊ 0⤋
Give them a try (typically 1 weeks will determine the fit, after your eyes have a chance to adjust). Any decent optometrist will honor a contact lens check after you have paid for the fitting to readdress any fit issues, including improper sizing of a contact lens.
It is also possible that the shape of your cornea (the base curve) has changed since your intial fit with the 8.5 base curve, depending on how long ago that was, so it may not be a problem.
2007-09-07 18:09:52 · answer #2 · answered by lunamiss 4 · 1⤊ 0⤋
Its not just about the base curve and the diameter, its all about the other stuff too. Do not worry about the numbers, its all about the fit. The doctor knows best. That is what they go to school for!
2007-09-07 21:42:56 · answer #3 · answered by A C 3 · 0⤊ 0⤋
Maybe they'll be better, maybe they'll be worse. Only your optomotrist can answer this. It sounds like she wants to get a feel for how the prescription works, rather than the fit. She may not have the correct size for you in her office that you can try, so she gave you these.
But just try them. You won't know until you put them in.
Best of luck.
2007-09-07 17:33:37 · answer #4 · answered by dancerhelen2006 3 · 0⤊ 0⤋