Showing posts with label Spectacles. Show all posts
Showing posts with label Spectacles. Show all posts

Importance of Interpupillary Distance in Spectacles

Importance of Interpupillary Distance

Globally approximately 145 million people of the total population and approximately 40% of India’s population is having an uncorrected refractive error (means need a pair of glass/spectacle).

Refractive error is one of the most important ocular conditions that are affecting all age groups and a priority under the VISION2020 initiative. Most refractive errors can be easily corrected at the primary care level with the help of spectacles. Uncorrected refractive error is the second leading cause of vision impairment in developing countries (including India).

Interpupillary distance (IPD) is the distance between the centers of your two eyes (center of corneal reflex) which is measured in millimeter. IPD can be measured monocularly and binocularly. Monocular IPD is the distance between the center of each eye and the center bridge of the nose. Monocular IPD may be slightly different for each eye due to anatomical variation and is dependent on your eye placement. An adult IPD usually remains more than kids IPD. IPD measurement is required for all types of spectacles including buying spectacles for distance or near. The near IPD is usually smaller than distance IPD due to convergence of the eyes together to fuse an object at near.

Different ways to measure IPD:

•    Ruler and torchlight (old method)
•    Pupillometer
•    Essilor Visioffice (USA)
•    Eye-Ruler 2 (USA) 
•    Zeiss i-Terminal2

IPD Measurement with Ruler and torchlight

Examiner should be exactly in front of the patient maintaining the same eye level height and holding a ruler at arm's length distance. Examiner closes his right eye and the patient must be looking at the examiner’s left eye with his right eye and put the ruler at the patient’s nose bridge area (for better stability) while aligning ‘0’ at patient’s center of the right eye. And without moving off a ruler examiner should open his right eye (after closing his left eye) and the patient must be looking at the examiner’s right eye with his left eye. Now measure the distance between both eyes center with ruler – this is your distance IPD. Average distance IPD may fall in the range of 56-66mm. The drawback of this method is parallax may skew measurement, examiner PD and patient’s PD must be very similar and the patient’s pupil must have the same size.
Another way to measure IPD is the distance between the right eye’s outer limbus to left eye’s inner limbus. With this method, IPD measurement may be inaccurate.

IPD measurement with Pupillometer

IPD measurement with pupillometer is more convenient. A Pupillometer has forehead rest, nose bridge, dial to change the distance to focus, display for monocular and binocular PD. Putting dial at infinite while using pupillometer over patient nose and aligning forehead rest. Now patient must be looking at small light inside the pupillometer and the examiner should align the measuring slide (a line or bar) until vertical lines should coincide with the corneal reflex. And read the reading in the display for monocular and binocular IPD. 
This device is faster than using manual measurement and takes all necessary measurements for personalized progressive lens and provides numerous solutions to select the lenses and frames. This device assesses the different measurement centers of eye rotation, the distance between pupils, the dominance of eye, reading distance, pantoscopic tilt, the fitting height of the lens, and frame parameters ie. wrap angle, A, B, and DBL.

Zeiss i-Terminal2

Zeiss i-Terminal2 is faster than using manual measurement and captures and calculates the patient’s required parameters with the click of a button. This device enables the measurement of highly ametropic patients through vergence control technology.  Measurement can be taken for any type of frame including large-size sunglasses and sports frames. It can measurement all height persons (children, taller or wheelchair person) ranging from ~120-208cms.

IPD is used to align the center of eyeglass lenses with the center of your eyes, which will give you a comfortable and relaxed vision. If the centers of eyeglass lenses are not aligned properly as per your eyes centration, then you may experience eyestrain, headaches, distorted vision, double vision, blurred vision, and/or an inability to wear your eyeglasses for a longer duration.

There are so many spectacle users (patients) who complain of eye strain. Many spectacle users are unsatisfactory that is the result of incorrect estimation of the IPD for distance and near. So it is an important While making a pair of glasses the dispensing professional need to measure Interpupillary distance (IPD) of a person.

IPD measurement is not the part of an eye examination but the IPD measurement is the responsibility of the dispensing professional and it is an important part of a spectacle prescription. Other spectacle dispensing services includes selection of an appropriate frame, lens type, lens thickness and coatings, adjustment of the spectacle frame, and proper alignment of the bifocal or progressive lens height.
Sometimes being perfect IPD alignment and proper spectacle lens fitting still patient complain of eye strain or unsatisfied. What could be the next to find for eye strain or unsatisfactory? So it is very useful scientifically to check the front and back curvature of the lens, coating of the lens, design (aspheric or conventional) of the lens of old glasses as sometimes spectacle users may not very satisfy with new glasses because of this. Sometimes new spectacle lens may have different front and back curvature, different coating of the lens, and design (aspheric or conventional) of the lens.

There are some more factors including frame size (bigger or smaller size over face), pantoscopic tilt (the amount of tilt on the front of the frame), wrap angle (the amount the frame is curved towards your face) and frame alignment over the face which can lead eye strain or unsatisfactory.

There are some other measurements that your optician will take when fitting you for progressive or multifocal lenses. There are two important key measurements - the IPD and the segment height must be checked while fitting a multifocal lens. These two measurements will be providing a comfortable vision with lesser adaptation time.

Each spectacle lens manufacturer is having its version of customized progressives. Near-pupillary distance measurement is also important in progressive addition lenses as these lenses are having customization instead of being standard. There are few other measurements including the vertex distance (the distance between the frame and the cornea), the pantascopic tilt, and the wrap angle to be checked while making a selection of a frame. The latest progressive lenses are more user friendly, giving a wider area of the field of vision and are generally easier to adapt to, especially for those with higher power prescriptions.

In my practice, if any patient complains of eye strain, double vision (shadow feeling while watching TV, or reading text at near), headache after wearing new glasses then my first check would be refraction (repeat power) check-up, IPD measurement, vertex distance, pantoscopic tilt, etc. Most patients are satisfied with repeat refraction and IPD measurement and their comfort changes after reassuring these two checks.

Progressive Lenses vs Bifocal Lenses

 Progressive Lenses vs Bifocal Lenses

  Approximately at the age of 40 (+/-2 years) your eyes gradually lose the ability to see things for near. It is a normal part of aging. The term is called “presbyopia”, comes from a Greek word which means “old eye.” You will probably find that you hold reading materials farther away or stretch hands in order to see them clearly.
When you are young, the lens is soft and flexible, easily changing shape due to this you can focus both distance and near objects clearly. After 40 years of age, the lens becomes more rigid and cannot change shape easily. This makes you to read at near with efforts, thread a needle, or do other close-up tasks. There is no way to stop or reverse the normal aging process that loses the ability to see things at near. However, this can be corrected with eyeglasses, contact lenses or surgery but surgical choice may not be very good for everyone. If you do not correct presbyopia, you may experience eye stress, eyestrain, focus-defocus, headaches and sometimes you feel that your hands shorten.
Wearing eyeglasses is an easy way to correct presbyopia. Seeing clear vision with eyeglasses offers the opportunity to select from different types of lens options, frame designs and even lens coatings for various purposes.
There are different types of eyeglass lens designs: single vision lens – corrects only one distance vision, bifocal lens – corrects distance and near vision (does not has intermediate distance to see monitor), and multifocal or progressive lens – designed to correct all distances vision (the upper portion is focused for distance vision, middle portion focused for monitor, while the bottom portion is used for reading).
Bifocals have two zones to correct vision for reading on the bottom half of the lens and another for seeing at a distance on the top. Some special lenses may also have segments at the top for those who need to look upward at objects that are in the intermediate or near range these lenses are called double-D bifocals (but not used frequently).
Progressive or multifocal lenses function generally the same way as bifocals due to a smooth transition between distance and near focal areas instead visible dividing lines in bifocal.
If you don't want to use glasses for distance, you can use reading glasses only which can be purchased from any optical store. You will probably must change your eyeglass prescription from time to time (approx every 1-2 years) between the ages of 40 and 60 because your eye's natural lens will still lose flexibility and consequently focusing ability.

Progressive Lens Designs

 Progressive Lens Designs

 Population age than 40 years having confusion that which type of glasses they should use! As they find discomfort while seeing ingredient/price tag on product or teaching their child(ren).
Glasses with distance and near vision correction are called bifocal. This comes with 'D shape' or 'Circle shape' or 'straight line' bifocal. This type of lens can give confusion in vision while walking, climbing up & down on stairs, when vision falls at the junction of distance and near segment. It is difficult to see monitor with this type of glasses. And person may experience back and neck pain.
Progressive lens provides clear vision in vertically (distance to near) without image jump but creates distortion in peripheral vision (side vision). But this distortion may depend on the design of progressive lens. Progressive lens comes in different field of vision ie. Narrow (hard design), medium and wider (soft design) field of vision progressive lens.
Wider field of vision progressive lenses are the best choice to use where user may have very less distortion in side vision, better comfort while adaptation, lesser adaptation time.
Progressive lenses are available with top brands like Essilor, Zeiss etc.

Online teaching could make kids vulnerable to Corona Virus

Online teaching could make kids vulnerable to Corona Virus

 In olden time kids were usually read books and was spending lesser time to screen (includes TV,  computer, etc). In the past few years teaching kids is not remaining same as earlier.

In the recent past, online education is rapidly increased due to competition among children. Most children take online classes due to nuclear-family as both parents go to work and parents can’t take them to coaching classes. Kids are spending lesser time in outdoor activities (lesser exposure in sunlight) as both parents are not having sufficient time to spend with them. Teachers also give them more creative activity as homework so kids use computers or mobile to search mostly.

Eye experts are informing parents of the dangers of increased digital screen-time on their children’s eyes due to online classes. Due to which children are at the risk of myopia (near-sightedness), dryness and redness of the eyes and disrupted sleep patterns. Dryness of the eyes can damage to the ocular surface (front surface of cornea) and could even make patients more susceptible to contracting COVID-19.

If someone use digital screen (including mobile, tablet, computer, laptop etc) and spending average 6-12 hours per day then their blink rate reduces along with that they could have symptoms of gritty sensation, itching, redness and dryness in the eyes. “When a person blinks, tears are liberated through tiny pores which lubricate the eye.

So kids also have lesser blink rate, pink eyes, and dryness of eyes while using screen and sometimes they are not expressing in front of parents. Most families may not have laptop or computer with them so mostly kids are taking classes in mobile phone.

“The patient can become vulnerable to catching an infection when their ocular defence mechanisms are down. Conjunctivitis is a common presentation among Covid-19 patients, indicating that people with dryness issues in their eyes are at risk of contracting the infection. As they touch their eyes due to dryness and irritation, and eyes are at risk of contracting the infection.

Why we are more sensitive to smart phone or tablet screen? Why we should restrict small screen usage?

1. Smart phone and tablet screen size is smaller than laptop or computer screen.
2. Smaller screen size means smaller font size in mobile and tablet screen.
3. Digital screen (mobile and tablet) is having sensors due to which screen brightness keep fluctuating with lighting conditions.
4. Mobiles, tablets and laptops screen usually have glossy screen where light reflection may occur but computer monitors are not having glossy screen.
5. Laptop and computer monitors do not have sensors to change the brightness and contrast automatically.
6. Good thing: mobile and tablets are more handy - whenever or wherever you want to use them, press the button and screen get on within a second.
7. Laptops are bulky; relatively screen size is bigger than a tablet but takes time to boot. A laptop has a glossy screen due to that reflection occurs.
8. Computers need more space and computer screen size is definitely bigger in all screens and takes time to boot. There are no sensors to change the brightness and contrast automatically and there is no glossy screen in monitor.

 Eye specialists advise parents to exercise caution by restricting screen time for children and incorporate regular breaks during class work.

Children who aren’t getting enough sunlight or change of scenery were at high risk of developing myopia or progression of myopia (worsening of nearsightedness). “Increased screen time will also lead to disruptions in their sleep patterns.” Eye specialist recommends an age-bracket approach to restricting screen time for children. “It is important that the number of teaching hours should be reduced greatly. If a child used to have eight hours of classes at school, the number of online hours cannot be of the same length.”

Computer use for children should be as follows (if needed):

-First standard classes should not be conducted online at all.
-Second to fifth class online classes should be 2-3 hours per day with the break of 30 minutes and parents should be involved for homework through email or Whatsapp.
-Sixth to eighth class online classes should be 3-4 hours per day with the break of 30 minutes and parents should be involved for homework through email or Whatsapp.
-Ninth to twelfth class online classes should be 4-6 hours per day with the break of 30 minutes and parents and teachers should be involved for homework through email or Whatsapp.

 Parents should be counseled that the kid should have some snacks, drink water and focus far objects during the break time. Room illumination should not be very bright or dull (semi dark) at the time of screen usage. Kids should not use screen in sleepy position and close to face. Parents should insist on kids to make book-reading habits. Book reading should always be in good illuminating room and sitting position. Books, mobile, and tablet should be kept at 30-35 cms distance from eyes. Computer monitor should be at least one hand’s-distance (50 cms) from eyes.

 If kids are getting any kind of discomfort in their eyes; they should:

1. Avoid excessive screen usage and eye rub.
2. Take water wet cloth and put it over closed eyes.
3. Frequent blinking during screen usage time.
4. After online classes kids should close their eyes and give rest to their eyes for one hour.

Children should follow computer vision syndrome (CVS) rules means take a 20 second-long break after every 20 minutes of screen time, and focus at something located 20 feet away.

Lubricating eye drops could be administered during the day to facilitate moisture on eye surface.

If kids rub their eyes then there is a risk to change the eyeball shape and glasses power may increase. Eye rubbing could sometimes lead as an eye allergy.

How to Start an Optical Business - Ideas & the Road Map | Optical Business

How to start an Optical business


WHO has been planned to eliminate blindness from the world by 2020. Globally 145 billion populations are having refractive error but some of them do not know about this. This refractive error can be corrected with glasses. An optometrist or an optician can correct the refractive error with glasses. So optical is a better and profitable business.

Globally eyewear market was counted as around USD 138 billion in 2019. And Indian eyewear market is around INR 85 billion in 2019. The optical market (Frames, lenses, and contact lens) is growing very fast in India day by day. Eye health awareness is playing a pivotal role in the growth of the optical business. Some of us showing our interest in optical business but unable to step-up due to a lack of experience and finance.

Optical business has wholesale and retail business. If you go for a retail business then you can sell spectacle frames, glasses lens, contact lenses, and accessories. But optical business can be started with 20-30K. If you have a very good plan then revenue generation would be high. Small business does not have to spend more in stock, advertisement and promotion but this advantage that they are essential of their community. They can generate revenue from their optical while highlighting the services that they provide to their customers/ patients.

Optical business can be planned:
a: Retail eyewear business (Own or associated with ophthalmologist).
b: Wholesale eyewear business
c: Online eyewear business.
d: Frame and glasses lens selling at eye camp.

Optical store sells eyewear that could be either corrective glasses, protective glasses or fashionable glasses, contact lens and accessories. Optical business is in other words healthcare business where you need to include patient care. Developing an optical business plan should be with the consult of an experienced successful business person. At first you need to decide the location of business, budget, or investment and vendors (from where you want to purchase the products). If you include an eye check-up facility in your business then it will increase sale value.

There are a few ideas:
Space Selection and budget:
Identifying a place for shop is very important. You need to select the place for an optical store in the main market area where you could get more customers. Optical store location should be roadside where the market is there and the shop facing should be towards the road. If the shop location is on the upper floors then customer entry would be very less.

Startup of optical business will vary depending on your own or rental place. Always better to start a business in your land or place but this will become very expensive. You need to have a 10x15 feet area for a medium-size optical store, where you cannot have an eye testing facility.

If you are starting a business in an urban prime location or shopping mall then the investment would be higher at that location. In prime location you can have higher value orders but expenses would be higher too. Prime located optical stores will not get much middle class or lower-middle-class customers. If you are starting an optical business in town or village area then the investment would be lesser compare to the urban area. In town or village you will get low to medium valued order and all variety of customers and business turnover would be lesser. If in case you have more customers than your turnover would be equal or more than urban business.

If you are an optometrist or optician and you start an optical store where your practice is good and local area peoples are happy with your work then your business growth will rise faster. If you are new to the business or starting a business in a new area, definitely this will take time to make the repo and grow the business.

If you include an eye check-up facility in an optical store then this will increase sale value. You need to have at least a space of 14x25 feet with an eye testing facility. For an eye check-up facility you need to have a unit chair, projector chart or complog (digital vision testing), trial set, trial frame, near vision card, retinoscope, auto-refractor (latest model with refraction and keratometer), Jackson’s cross cylinder, lensometer, etc. If you want to employ an optometrist or ophthalmologist in your practice, this will make super practice in your area.

You can start an optical store in shopping malls where customers usually look for fashionable eyewear and goggles. Another place to start an optical store is near government hospitals where you can sell glasses for poor people.

Business ads can be placed in the school program, community events which will improve publicity and reputation in the community.
Optical business license:
Optical business needs an Optical trade license for your optical like other business. This license can be obtained from local and national optical associations.
Interior design and space:
All-optical stores are types of healthcare stores where you need to have cleanliness and hygiene. You should consult with an interior designer or experienced successful optical business person for proper placement of racks, billing counter, technology utilization, and attractive decoration of the optical store. Another important place should be for the fitting section and work-shop in optical interior design. Self-illuminated frame racks with matching wall colors give attraction to customers. Proper interior design gives positive reflection in business. Optical stores should have sufficient seating places for customer and their family members.
Technology Utilization:
Today’s world is filled with technology and a business plan should include a security plan with a Camera surveillance system. So Shoplifters or staff member should not steal expensive frames and money.
Tools for optical store:
You should maintain maximum tools for optical stores for smooth functioning. Lensometer is the primary tool for optical stores. It is available in manual and automatic mode; an automatic lensometer is expensive than manual. Manual lensometer is available in Indian brands and imported brands (Topcon). Expertise is required to use a manual lensometer. Optical store is equipped with check-up facility then you need unit chair attached with a slit lamp biomicroscope and tonometer, trial set, trial frame, projector chart or Complog (digital vision testing), near vision card, retinoscope, auto-refractor (latest model with refraction and keratometer), Jackson’s cross cylinder. Autorefractor attracts the customer but does not give accurate refraction values. If you are not financially strong then you can purchase secondhand instruments.

Another important tool for optical store is fitting machine and workshop by which you can fit single vision glasses within few minutes and repair glasses. Fitting time and delivery of a glass is the key factor for successful optical business.
Product and supplier:
A small to medium optical business should have 6-8 vendors for spectacle frames. By which you can have better relations, extra volume discounts, and easy payment process. You need to do market research and know what people are wearing and in which brand customers are attracting more. You need to watch the fashion trend to know more about the foreshadow eyewear trend. Once you know what design your customer prefers more or you want to focus on a particular design then you should have a good relationship with the supplier. So, you need to choose a supplier very wisely. This would convert into more flexibility, minimum quantities, greater growth, and quicker delivery to customers.
Nowadays social media advertising is very much popular so advertising on Facebook, Twitter, etc will keep your practice visible to the community and providing no-cost promotion. You can display a promotional offer in your practice. You can collect customer’s phone numbers and email ids that are coming to your store so that they can take promotional offer benefits given by you. You need to use some metrics so that you can know how is your optical business performing?
You can make your business website so that customers can receive value-added services.
At last but not the least optical opening ceremony:
While opening ceremony of the optical store you should invite MP/MLA/Chairman or Sarpanch so that your business popularity will increase.

Safety Glasses

Safety or Protective Glasses

Safety glasses or goggles are forms of safety or protective eye glasses at work that usually protects the eyes and surrounding of it. Safety or protective glasses can be used any time for any purpose.
Mostly injury eye injury occurs with flying particles. Next most common eye injuries can happen due to chemical splash. As per The Occupational Safety And Health Administration’ (OSHA’s) eye and face protection standards “the employer shall ensure that each employee uses appropriate face and eye protection when exposed to facial hazard from flying particles (metal or wood chips), molten (hot) metal, liquid chemicals, acids, caustic soda, dried lime powder, chemical vapour or gases and potentially dangerous light radiations (ultraviolet or infrared radiation exposure). Chemicals fall or foreign particles or objects in the eye cut or scrapes or damage the tissues in the eye are common eye injuries that occur at work.

Workers experience eye injuries at the work place for two major reasons:
*Workers were not wearing eye protection.
* Workers were wearing the wrong kind of protection at work.

As per OSHA, personal protective eyewear such as safety glasses, goggles, face shields or full face respirators must be used. The necessary eye and face protection depends upon the type of hazard, the circumstances of exposure, other protective or safety equipment used and individual vision needs.

How to protect face and eyes from injury?

* At work worker should know about facial and eye safety danger.

* Before starting work eliminate hazards by using screen guards (machine), work screens and other safety engineering controls.
* Use proper eye and face protective wear.
* Keep your safety eyewear in good condition at safe place and should be replaced if it is damaged.
There are different types of protective glasses:
Safety glasses with prescription or non-prescription are designed to provide significant eye protection. Safety glasses should have polycarbonate or Trivex or equivalent lenses with shell full frames large size. Safety glasses should be following American National Standard Institute (ANSI) standard. Safety glasses provide eyes protection from foreign bodies, dust, chips and flying particles. Safety glasses should be wraparound style which provides additional side protection.
Protective goggles can provide protection from direct dust and chemical splash. Wraparound safety goggles provide a secure shield around the eye and protect from any type of hazard coming from any directions. Safety or protective goggles can be worn over contact lenses.
Special filtered protective goggles protect the eyes from optical radiations exposure (welding or working with lasers).
          Safety glasses lenses should be made with Polycarbonate or Trivex material to provide highest level of protection from impact.

Glasses and Contact Lens comparison


Glasses are used externally but contact lenses used over cornea (over black eyeball).

Glasses give you lesser field of view and contact lenses give wider field of view and natural vision.

Glasses cost depend on frame and lenses quality but contact lenses starts with the range of Rs 1000 ( MRP in Indian markets).

Glasses need less maintenance but contact lenses need little more maintenance (compare with glasses).

Glasses and lenses are available in UV and non-UV protection but few contact lenses are UV protected.

Glasses get fog with temperature change but contact lenses do not fog.

Glasses are uncomfortable and slippy over nose and ear but  contact lenses do  not has

Contact lenses can change your eye colour temporarily (especially for parties and functions) but with glasses you can not.

Glasses can be worn or remove any time as per convenience but contact lenses need more  hygiene.

High prescription of glasses  are heavy over nose and ear - may cause sinus congestion migraine and discomfort but contact lenses do not has.