Digital imaging in Indian optometry clinic--relevance & implementation

Transcription

1 Digital imaging in Indian optometry clinic--relevance & implementation -Rajesh Wadhwa M.Optom B.Sc.Hons.(Ophth.Tech.)(AIIMS) B.Sc.Hons.(DU); FIACLE;PGDHRM Digital imaging is simply the use of technology for creation of images that are digitized, typically from a physical scene. To an optometrist, the subject of primary interest (physical scene) is the human eye and we shall consider here imaging of eye-surface and of fundus. At times one may wonder if at all digital imaging is relevant to Indian optometrist. Considering the varied applications where this technique is useful, the most judicious inference is YES. In India, the optometrist can use digital imaging techniques in several cases like recording contact lens fitting (including fluorescein pattern), imaging a suspicious glaucomatous cup, documenting a pre-existing retinal or corneal lesion, getting the image of wider zone of retina for analysis (when compared to field seen by direct ophthalmoscopy) and many similar applications. As you read through, you will be able see that the procedure of imaging is simple. We shall also discuss why digital imaging is required. A mention of glaucoma & more elaborate explanation of diabetic retinopathy will be included before reasoning out the advantages that this technology has to offer to an Indian optometrist. Fig 1: Few images taken by author during learning phase 1

2 This manuscript talks of methods that an Indian optometrist can adopt to perf perform orm digital imaging of the eye. The instrument used by the author for digital imaging is non-mydriatic non fundus camera by Optomed (M5). Procedure for digital imaging with non non-mydriatic Optomed camera: This instrument is small and can fit into a small closet or drawer. It comes with two attachments, one for or fundus-imaging & other for eye-surface surface imaging. Eye surface can be imaged in white light or with blue option (for fluorescein patterns).. Retina can be imaged with white light or with red red-free free filter f (for nerve fiber layer analysis). Still & video both kinds of imaging can be done by this instrument. Fig 2: Optomed camera in its cradle Fig 3: The fundus attachment Fig 4: The eye-surface surface attachment Process is simple, no medicines, no invasive steps, just point and click with all guidance on screen. The images here are self explanatory. Fig 5:: Eye surface image seen directly on screen Fig 6:: Fundus imaging. Red box on screen turns green when best focus ocus is auto-achieved 2

3 USB Fig 7: After taking images, simple USB data transfer as in regular cameras Fig 8: A small printer prints quality images in less than 1 minute These images can be processed, analyzed, ed or even printed instantly. Printing can be done by a stand-alone printer that is readily available and gives 4x6 inch prints of high quality (with OD or OS marked at bottom corner). Why in India : Of the world s 37 million blind, India owns 15 million. Among the visually impaired population of India, 52 million are not functional because of lack of spectacles. Of these 11 million are children with uncorrected refractive error. Of the total visual impairment or blindness, over 75% is preventable or treatable or avoidable. Optometrist is the first line of defense against blindness. Optometrist has a role to play in all major causes of blindness in India. Of the total visual impairment in India, over 50% is because of unoperated cataract. Optometrist uses residual vision of patient and enhances to best corrected visual acuity by giving appropriate refractive correction. Primary health-care responsibility of optometrist is to attend to uncorrected refractive error (which accounts for over 21% of visual impairment in India). 13% glaucoma is better managed by early detection. 5 % diabetic retinopathy is becoming a big issue since it accounts for 26% of avoidable blindness. Optometrists in India are at the launch-pad of widening their horizons in direct management or early detection of all these conditions and thus to have a greater role in helping the nation in fight against blindness. Often a question is asked What does it mean to be visually impaired? Indian optometrist is sensitive to this question. We know that visual impairment & poverty support each other. Bread-earning opportunities & social standing, both are adversely affected with poor visual performance. A sample study has shown that 64% people are driven into poverty within 5 years of having been struck blind. 3

4 Every optometrist is concerned if someone suffers due to avoidable visual impairment. One can realize the pain of a village-tailor who turns presbyope & cannot earn his livelihood due to lack of spectacles or ailments like age-related macular degeneration or diabetic retinopathy. Several office-goers lose their peripheral field of vision due to glaucoma & cannot drive to office. A large percentage is struck blind due to diabetic retinopathy. Optometrists routinely perform direct ophthalmoscopy by peeping through undilated pupil. While this gives a small zone of retina as the assessable field, a dilated pupil can give a wider view. Irony is that Indian optometrist does not dilate the pupils. We wish to examine a wider part of retina to be more authentic. Therefore, a non-mydriatic camera that gives images of wider zone of fundus is the need. In order to manage glaucoma/diabetic retinopathy/hypertensive retinopathy/other retinal or corneal lesions, we need to compare the findings of present day with those of older encounters. For this, there is no better way than to have images. Recordings of ophthalmoscopy that are drawn on paper are based on skill and memory. When we compare various methods of fundus examination that are routinely used in India, we list the following: a) Direct ophthalmoscope gives approx 6 to 8 degrees of zone b) Indirect gives wider view but needs dilation & consumes lot of time c) Non-mydriatic camera gives upto 40 degrees of coverage in few seconds and can image eye-surface also. Such an instrument can be considered as an alternative or complement to ophthalmoscopy by imaging. While glaucoma can have a battery of tests, imaging the ONH is important. A large cup: disc ratio, baring of circumlinear vessel, bending of vessels at the edge of cup, a splinter hemorrhage at disc margin, focal disc damage are all captured in the images for analysis. The camera has a red-free mode that gives inputs for nerve fiber layer analysis. Digital imaging is very important for detecting & managing diabetic retinopathy. We need to emphasize on significance of diabetic retinopathy because it is very crucial for India to mange this condition. Sooner or later, every diabetic will have diabetic retinopathy (DR). Usually after 10 years of standing diabetes. This means that blindness due to DR is directly proportional to number of diabetics. People with Diabetes Mellitus (DM) are at risk of losing vision. We may delay or prevent diabetic retinopathy effects by medical management of DM & with lasers BUT we cannot reverse the harm that DR may have done. If we look at available & projected statistical values, in world: Comparison between 2010 data & projected 2030 figures, there will be an increase of 54% diabetics (will be around 440 million). This means that for every 2 diabetics, there will be 3 diabetics by This will not be uniform. Higher percentage is expected in poorer countries. While the world average of increase in number of diabetics by the year 2030 will be 54%, the expected increase in India is 72%. Quoting Dr Rajiv Raman (in 2010), senior consultant, Sankara Nethralaya : India, the world's diabetes capital, has another reason to worry. Diabetic retinopathy is the sixth cause of 4

5 blindness in the country. "From being the 17th cause of blindness in the country 20 years ago it has become the sixth cause with 18% of diabetics above 40 having diabetic retinopathy. This is a cause of worry". Gaining time: One ray of hope is that since there is 10 to 20 years delay in onset of DR after diabetes strikes, we still have a window of time to put our systems in place. These systems can be developed for early detection of diabetes & of DR both. Such an act will be a concrete pre-requisite to contain the visual loss due to diabetic retinopathy. This supports the fact that eye-care professionals at every level should have resources to screen for DR and a wide field fundus imaging by non-mydriatic camera seems to be a simple & effective solution. Fig 9: Diabetic retinopathy photographed by author in Sep.2012 It is also good to understand a little more about DM and to understand how it affects the eye. Diabetes mellitus, or simply diabetes, is a group of metabolic diseases in which a person has high blood sugar, either because the pancreas does not produce enough insulin, or because cells do not respond to the insulin that is produced. There are two major groups of diabetics Type 1 diabetes: Uncommon, caused by destruction of insulin-secreting cells Type 2 diabetes: Develops slowly, with age, urban life-style & has close association with obesity Both types of Diabetes mellitus cause complications, especially due to damage to small blood vessels In Diabetic Retinopathy (DR), damaged blood vessels leak in the retina. Later the blood vessels get blocked. This leads to formation of abnormal new blood vessels. These new vessels are fragile and can easily bleed into vitreous. These can also pull the retina & cause retinal detachment. If the damage to vessels is in central retina, it causes diabetic-maculopathy & swelling of retina. One may see several retinal lesions in diabetic retinopathy like hemorrhages & microaneurysms, venous beading, Intraretinal microvascular anomalies (IRMA), new vessels (key characteristic of proliferative diabetic retinopathy), pre-retinal hemorrhage (a sign of proliferative diabetic retinopathy). At times most of these can be found in one image. 5 Fig 10: Most of DR findings in one image (credits of image to anonymous) Whose name is to be written on clicked image: These images are clicked and possessed by the respective authors as

6 owner. If you click certain images, whole world will quote acknowledgement to your name whenever the image is used. Conventional method of recording retinal lesions is to draw images. One can document various lesions as per conventionally onventionally defined color codes. When digital imaging was a rare resource, following rules were followed by the practitioners wanting to document the state of fundus. Fig 11 :Conventional Conventional Color Scheme for Retinal Mapping -R Red: Light red: attached retina Dark red: retinal arteries, preretinal or intraretinal hemorrhages -Light blue: Retinal Detachment -D Dark blue: Retinal veins, margins of retinal breaks, lattice is outlined in blue with inside crosslined --Black:: chorioretinal pigmentation -Y Yellow: intraretinal or subretinal exudates -B Brown: nevi, melanomas, choroidal detachment -G Green: vitreous or lens opacities Opacities in media, vitreous hemorrhage Rather than going through all these rules painstakingly, it seems easier to click an image and preserve with all accuracies already built built-in. We come to the question of feasibility easibility of fundus imaging in Indian optometry clinic. clinic Author accepted to use this camera because the feasibility was obvious. Most attractive reasons for choosing Optomed non-mydriatic mydriatic camera were no dilatation, no o structural changes required in clinic, can an fit into drawers drawers, 10 minutes to image & to give printt out, out good for diabetic retinopathy, glaucoma etc. It is a known fact that taking images through non non-mydriatic fundus camera are more m sensitive than ophthalmoscopy, images mages can be zoomed zoomed, images mages can be further processed through software, measurements can be more accurate and iff there is an image of previous encounter, more reliable decisions can be made in follow follow-up visits. Since a large field is captured byy Optomed camera despite non non-dilation lation of pupil, several findings are easy to capture. Here I quote aan example where I almost missed these lesions with direct ophthalmoscopy. The image shown below was taken initially for documentation only as the patient was a known diabetic for 6 months. Two small lesions were seen in field that was 6

7 already missed in routine direct ophthalmoscopy. The presence of these lesions was then ascertained by having a re-look with direct ophthalmoscope. Fig 12: An early lesion of diabetic retinopathy that was easy to miss by direct ophthalmoscopy but could be seen easily in image taken by Optomed non-mydriatic camera As is known, early detection of diabetic retinopathy can lead to good management (mostly systemic by physician and/or by lasers). These images can be further enhanced by regular windows software for better interpretation. These enhancements can be in auto-correction of image or in modified gradient tint. Optomed provides special software that can give sectorial magnification and facility of marking arrows & labels on the captured image. Few examples of enhancement are shown here Fig 13: Same image after auto-correct-image command Fig 14: Image after auto-graduated- tint command to show cup:disc ratio Why did I not have a fundus camera so far 7

8 In various lectures that the author has been delivering on the subject, often it is asked why did you not have a fundus camera earlier? This leads to finding the bottle-necks and barriers to acquisition of such an instrument in Indian scenario. Common issues are: Which one to buy What is the budget required How soon will the instrument pay back (expected in 1 yr with 3 Px per day) Who will teach the skills of using it How can I do that as a drug-less procedure What will I gain after getting the camera Answers to all these questions now look simple: Criterion of which instrument to buy: A non-mydriatic camera that takes less space in clinic, no medicines required, gives wide angle of view (around 40 degrees or more), can image still & video images both, can image eye-surface also (including fluorescein pattern of contact lenses & lesions that get stained with fluorescein) and can give red-free fundus images. The instrument should be easy to use and not be time consuming. Good quality of images to be captured without disturbing the pre-existing physical space of clinic. Managing cost (what is the budget required & how soon will the instrument pay back): This is a commercial question not meant to be answered in a professional article. However, an idea can be had if we say that the instrument pays back for its price in one year. Calculation has been done assuming that one image (of one eye) is charged at a nominal Rs.300/- and on average only three patients are imaged on every working day. Time taken is less than 1 year for instrument to pay back for itself in monetary terms. Learning skills: An example of author s experience explains itself. The instrument is so well automated and easy to use that after 10 minutes of talking to a fresh audience, all 15 attendees could take excellent images with confidence on Optomed non-mydriatic fundus camera. Advantages beyond revenue generation: Foremost is that society will benefit by early detection, good documentation and therefore in prevention of avoidable blindness (especially in cases of diabetic retinopathy, hypertensive retinopathy, glaucoma etc.) 8

9 This will be another aspect of optometric practice that will create higher levels of loyalty and also the patients will feel gratified by the care they receive. (This is good message to patients that we provide best possible eye-care at minimum possible cost) Data collected & published results by optometrists will go a long way in recognizing their potential. This data can be used in planning & management of eye-care at regional & national levels. When such facility is provided at eye-camps, the data becomes all the more significant. Fig 15 : An example of how eye camp data can be documented for diabetic retinopathy. This data is analyzed after the camp is over by viewing the images (in office) ), thereby being authentic, supported by documentation and also fruitful in delivering the purpose of the camp. One can not overlook the fact that in India several optometrists are associated with optical outlets. In today s times of retail competition & online sales, service is becoming very important (because service is not available online). Most optometrists who are attached to optical outlets can add this as a rare service. Procedure is drug-less therefore there is no legal binding. This kind of service adds a new flow of footfall through old patients & through referrals. When an optometrist captures an image, he/she gets the credits as did the author in few images below: 9

10 Fig 16: Healed CSR (?) in 25 years old male Fig 17: High cup-disc ratio (magnified with provided software) With this brief explanation, it is clear that every optometrist of India can be more involved in fight against blindness by adding non-mydriatic fundus camera in the clinic For any further enquiries, author, Rajesh Wadhwa can be contacted: phone Acknowledgements & references: i. Sarthak Wadhwa (B.Optom) for imaging of procedure & equipment ii. Piyush Wadhwa (B.Optom) for help in content iii. Optomed (for support in supply of information & equipment) iv. IDF diabetes atlas 4 th Ed v. Community eye health journal Vol24/Issue 75/Sep2011 vi. The role of optometrists in India: An integral part of eye health team by Rajesh Wadhwa et.al in Indian Journal of Ophthalmology Vol.60/No:5 10