Fitting Principles PDF

Fitting Principles  Properlyfitting eyeglasses is important for the comfort and safety of wearer. The eye-care professional should know how to fit eyeglasses Introduction A pair of eyeglasses can be the best fashion accessory. But it’s just as important for the glasses to fit correc...

Fitting Principles  Properlyfitting eyeglasses is important for the comfort and safety of wearer. The eye-care professional should know how to fit eyeglasses Introduction A pair of eyeglasses can be the best fashion accessory. But it’s just as important for the glasses to fit correctly. o Poorly fitting glasses don’t look good, and can detract from the polished appearance. o If the glasses don’t fit well, they can press uncomfortably against the ears, slide down the nose, fall off or pinch the bridge of the nose. o When the patient feels uncomfortable, he may not wear the glasses as often as he should. o If the glasses don’t fit as they should, they may not be correcting the vision properly Why Is It Important to Fit Eyeglasses Properly?  Visually checks 3 points: o Crest of Nose (Bridge) o Above Right Ear-Crest o Above Left Ear-Crest  Check for gaps between the temple and skull.  Do not use the ears to hold the glasses in place (adhering to the skull*)  The ears are to act only as a stop, not to hold glasses. The Fitting Triangle When fitting eyeglasses, we need to check four: 1. The frame (Straight imp) 2. The temples 3. The bridge, or nosepiece 4. The pupil position (centrd) How To Tell if the Eyeglasses Fit Well  Frame: A well-fitting eyeglass frame will be slightly wider than the face. It should be wide enough so that the temples do not touch the head, but not so wide that there is a large gap between the temple and the face. (MBS Consideration as well) The wearer should be able to fit a finger between the temple and his face.  Temples: If the frame is too small, the temples will actually touch the face, and angle outward as they extend to the ears. The wearer wants the temples to extend straight back and to touch his head just before the ear. The temples also need to be long enough to curve when they reach the ear, and not before. If it curves too early, it can push the frame up, forcing it down on the nose. How To Tell if the Eyeglasses Fit Well Basic frame alignments A: When temples too tight, spread temples B: When temples too loose, bring temples in C: When just right, temples touch head with no pressure How To Tell if the Eyeglasses Fit Well The optician must stand up, look and feel behind the ears, and then look down over the top of the patient's head to acquire the above view of the fitting triangle. Use hands to manipulate the head, the frame, and to feel the temple ends. Temple-touch must not exert pressure on either side of head! How To Tell if the Eyeglasses Fit Well  Bridge or nosepiece: The bridge, or nosepiece, joins the two lenses and fits across the nose It should fit snugly against the bridge of the nose. With a plastic frame only minimal adjustments can be made to the bridge. Care should be taken during frame selection to ensure a proper fit. The sides of the bridge should come in contact with the length of the nose. Adjustable nose pads should be adjusted so the frame sits comfortably on the patient’s bridge with the pupils falling slightly above the vertical center of the frame. Adjustments should be made to bring the maximum surface area of the pad in contact with the patient’s nose. (shouldn’t be tilted!) Use the nose pad pliers for these adjustments. How To Tell if the Eyeglasses Fit Well Bridge width: The horizontal distance between the pads when viewed from the front. How To Tell if the Eyeglasses Fit Well Frontal angle: Angle of the pads when viewed from the front of the frame. The tops of the pads should be slightly closer together than the bottoms of the pad following the contours of the nose as it gets wider from top to bottom. Splay angle: The angle of the pads when viewed from the top of the frame. The front edges of the pads should be closer together than the back edges. How To Tell if the Eyeglasses Fit Well Vertical angle: The angle of the pads when viewed from the side of the frame. Since most frames will have some amount of pantoscopic tilt, the bottoms of the pads should be slightly closer to the frame front than the tops. How To Tell if the Eyeglasses Fit Well Pupil position: The distance between the pupils is an important measurement. The optician will measure this distance, so the lab making the lenses can place the correction in the proper area. The pupils should be close to the center of the lenses. Glasses that fit properly will not rest on cheeks or touch brows. In addition, they should stay in position, no matter what happen. How To Tell if the Eyeglasses Fit Well Why does pupil position matter? Position of Wear: Describes how your client’s fitted eyewear has repositioned their lenses from those used to test their vision in the exam room. WHAT IS POSITION OF WEAR? POW is EXTREMELY important in fitting any type of ophthalmic lenses ◦ High powered ◦ Bifo-s ◦ Multifo-s What are multifocals ? There are two ways to take position of wear measurements: manually and digitally. With either way, the most essential requirement is repeatability. The frame style selected must be fitted to the preferred position before these measurements are taken. (ask PX to wear it) WHAT IS POSITION OF WEAR? What is PD? (Also called Pupillary Distance, Inter-Pupillary Distance or Pupil Distance)  PD is the distance between the centre of one pupil to the centre of the other pupil.  Prescription glasses are made so that the distance between the optical centres of the glasses lenses, is the same as PD.  PD varies from person to person but once adult; PD does not change even if spectacle prescription has changed.  PD is measured either during the eye test or when prescription glasses are ordered. Pupillary Distance (PD) 1- PD Rulers: One of the first and most basic tools for the optician is the PD (Pupillary Distance) Ruler. This ruler is normally 15 centimetres long; each centimetre is subdivided into millimetres. The PD Ruler can be used for measuring frame dimensions, as well as for measuring pupillary distance. Some PD rulers are made of plastic, while others are made of metal or wood. How to determine eye PD 2- Pupillometer:  When a patient orders new glasses; the optician uses a pupilometer to determine the distance between the center of his nose and each pupil (could differ)  The pupilometer gives a much more accurate reading.  Used for measuring of monocular and binocular pupillary distances for all distances between 35cm and infinity.  Monocular pupillary distances can be measured by occluding one eye if the patient’s binocular vision is abnormal.  Monocular and total pupillary distances (from 48 to 77mm) are measured in 0.5mm steps. How to determine eye PD When to use Mono or Bino PD? 3-Lensometer and Digital lensmeter Measure PD on eyeglasses A lensmeter also called vertometer or focimeter measures the optical properties of a pair of eyeglasses. It's an ophthalmic instrument that's most often used to ensure that a pair of eyeglasses has been ground to the correct prescription and correct PD. How to determine eye PD Digital lensmeter give Quick and accurate measurements. All lenses are automatically calculated with precision and speed. It can simultaneously capture the PD of frames and power of lens with high fidelity. How to determine eye PD How to determine eye PD Pupil Heights: When obtaining heights, maintaining appropriate and dispenser posture is challenging. How To Tell if the Eyeglasses Fit Well Vertex Distance Distance from the back of the lens to the front of the eye. This can be measured by using a PD ruler, or ideally by the use of a manufacturer's specialized measurement tool distometer. How To Tell if the Eyeglasses Fit Well Pantoscopic Tilt The most important aspect of proper pantoscopic measurement is to be sure that the client’s facial plane is as vertical as possible before the measurement is made. Pantoscopic tilt can be measured by using Rodenstock pantoscopic tilt Ruler, Hoya, essilor…. How To Tell if the Eyeglasses Fit Well How To Tell if the Eyeglasses Fit Well  Face Form Wrap Angle Also known as face form angle and panoramic angle. We can use a dedicated frame wrap measuring device, such as the Shamir Panorameter* The optician places the unit on both lenses so the small curves in the wedged shaped pieces fit flush to the lens. In this position, a pointer indicates the amount of face- form tilt (wrap) in the eyewear. Wraps are typically 12 to 18 degrees of facial wrap (face form). How To Tell if the Eyeglasses Fit Well How To Tell if the Eyeglasses Fit Well How To Tell if the Eyeglasses Fit Well Exam Room Vs Fitted Frames 1. Vertex Distance: Averages 10 to 14mm. 2. Pantoscopic Tilt: Lenses of a phoroptor or trial frame are straight up and down, i.e., zero pantoscopic tilt. 3. Face Form Angle: Lenses are held in an absolutely flat plane, i.e., zero face form angle. 4. Pupillary Alignment: Particularly with phoroptors, they accommodate IPD in a binocular manner, and therefore cannot make allowances for monocular eye separation differences. 5. Pupillary Height—: The patient’s eye is typically aligned with the geometric (optical) center of the phoroptor’s test lenses. Exam Room 1. Vertex Distance: Fitted values can range from as close as 8mm to as far as 20mm. 2. Pantoscopic Tilt: Fitted values range from 0 to 14˚; typically 3 to 7˚. 3. Face Form Angle: Also known as frame wrap angle, fitted values range from 0 to 10 degrees. Wraparound sunglasses can range from 12 to as much as 25 degrees. 4. Pupillary Alignment: If measured ideally, individual (monocular) values are taken. Differences between the eyes may range up to 4mm. 5. Pupillary Height: Fitted values often find the pupil placed in most lens shapes between 3 and 7mm above the geometric (and in some cases, the optical) center of the lenses.  Position of wear compensation takes these differences into account. Fitted Eyewear Fitted eyewear The size of frames can affect the look of the glasses on the face and how comfortable they are to wear: o The top edge of the frames should be no higher than the line of your eyebrows. o The bridge design and position is the key to a comfortable fit. o The lower edge of the frames should not sit on your cheeks, even when you smile, so that they don't rub or irritate. o The size should be in proportion to your face - if you have a small face, don't choose large glasses. o The width of the frames should not be wider than the overall width of your face at the temples. The correct fit