B, Distribution of CP per capita. The same countries as in A are represented. The continuous vertical line, almost merged with the y-axis, shows the median 0. The dotted vertical line shows the median In A and B, yellow bars show countries for which we deemed the data of questionable robustness. Hatched bars indicate countries for which we deemed the data of questionable robustness.
The boundaries shown on this map do not imply any opinion by the authors regarding the legal status of any country or territory or its authorities or regarding the delimitation of frontiers or boundaries.
JAMA Ophthalmol. Importance Corneal transplantation restores visual function when visual impairment caused by a corneal disease becomes too severe. Objective To describe the worldwide situation of corneal transplantation supply and demand. Design, Setting, and Participants Data were collected between August and August from a systematic review of published literature in parallel with national and international reports on corneal transplantation and eye banking.
Interviews were performed during international ophthalmology or eye-banking congresses or by telephone or email. Data were collected from countries. Main Outcomes and Measures Corneal transplantation and corneal procurements per capita in each country.
The United States, with Corneas were procured in only 82 countries. Only the United States and Sri Lanka exported large numbers of donor corneas. Conclusions and Relevance Our survey globally quantified the considerable shortage of corneal graft tissue, with only 1 cornea available for 70 needed. Corneal transplantation CT is the most frequently performed type of transplant worldwide.
It restores visual function when impairment caused by corneal damage is deemed too severe to provide acceptable quality of life in the country where it is performed. Corneal blindness is the third leading cause of blindness worldwide after cataract and glaucoma, 1 with 10 million people having bilateral corneal blindness. Organ and tissue transplantation is a complex process with many legal, ethical, religious, and cultural barriers. However, the cornea presents several characteristics that make storage and transplantation easier than other tissue and organs, and eye banks EB , responsible for storage, quality, and safety controls, are instrumental in CT success worldwide.
From a surgical viewpoint, conventional CT is also called penetrating keratoplasty. It is the dominant technique worldwide and involves replacing the full corneal thickness. In the past 10 years, lamellar grafts have developed quickly through progress in concepts and instrumentation.
There is currently no practical alternative to CT for most cases worldwide. Given that defining comprehensive strategies to fight corneal blindness requires precise knowledge of global supply of and demand for corneal graft tissue, and that cornea donation can also be an indicator for the donation of organs and other tissues, we designed the most exhaustive possible global study and report its findings here.
These provide previously unavailable evidence of the global imbalance in donor cornea supply and demand. With an estimated With We conducted a global, transversal, and descriptive epidemiological study between August and August Forty-two countries with a population of less than 1 million at the time of the survey 34 of which likely had no corneal procurement or CT activity were excluded. According to United Nations demographic statistics, this left countries, ie, It was conducted in 2 steps for each country.
This long period was necessary to gather the maximum amount of data, especially for countries with rare reports, and, for others, to analyze whether significant changes occurred over time. Whenever multiple data were available, only the latest were considered.
We collated their latest reports on CT and EB. Similar statistics from and were also obtained from the websites of health ministries and organ and tissue organizations. In step 2, we conducted interviews using the standard questionnaire in the Box.
To increase the accuracy of the answers for each country, 1 or more respondents were needed to validate the interview results, unless national reports were available. The minimum number of participants for this task 1, 2, or 3 was determined by country population size and the number of active ophthalmologists.
The interviews were conducted in various forms by 5 investigators R. We first conducted face-to-face interviews at 11 international congresses that covered clinical ophthalmology, ophthalmic research, and eye banking eTable 1 in the Supplement. Priority for the face-to-face interviews was given to people working in countries where data were not yet available. Following these interviews, the respondents were encouraged to cross-check and report back additional data on returning to work.
In parallel, specialists were contacted by telephone and email. Mailing lists were obtained from board members of national and international ophthalmic and eye-banking associations. Data were checked for consistency and accuracy. Numbers that appeared abnormally large or small were cross-checked with additional contacts.
For each country, the data sets obtained through steps 1 and 2 were compared and collated. Published data and national reports took precedence over individual interviews. Countries were classified in homogeneous groups in terms of balanced supply and demand.
These groups were formed to represent pragmatically each national situation. We first calculated procurement and transplantation rates per million inhabitants in each country and classified each rate using 6 categories eTable 2 in the Supplement. We assigned the same weight to both rates, so as not to artificially favor importing countries over those with comparable CT activity using nationally procured donor tissue.
We therefore added the 2 scores to obtain a total score between 0 and A bonus point was given to countries that were significant exporters of donor corneas. Finally, based on the total scores, a 7-group classification eTable 2 in the Supplement was selected after it was deemed to best reflect the classification of the 10 test countries of which we had expert knowledge.
A world map was then generated using a 7-color code. Data were expressed as median interquartile range [IQR] for nonnormal distribution. Eighty-two national and international statistical reports on CT or EB and relevant published articles were analyzed and collated.
For the countries with data, data-reliability score distribution was similar for CT and EB. The median was 6. A cornea transplant is an operation to remove all or part of a damaged cornea and replace it with healthy donor tissue. A cornea transplant is often referred to as keratoplasty or a corneal graft. It can be used to improve sight, relieve pain and treat severe infection or damage.
One of the most common reasons for a cornea transplant is a condition called keratoconus, which causes the cornea to change shape. The cornea is the clear outer layer at the front of the eyeball. It acts as a window to the eye.
The coloured iris and the pupil the black dot in the centre of the iris can be seen through the cornea. The cornea helps to focus light rays on to the retina the light-sensitive film at the back of the eye. This "picture" is then transmitted to the brain. When the cornea is damaged, it can become less transparent or its shape can change.
This can prevent light reaching the retina and causes the picture transmitted to the brain to be distorted or unclear. The type of cornea transplant you have will depend on which part of the cornea is damaged or how much of the cornea needs replacing.
A cornea transplant can be carried out under general anaesthetic where you're unconscious or local anaesthetic where the area is numbed and you're awake. The surgery usually takes less than an hour and, depending on your circumstances, you either leave hospital the same day or stay overnight.
A human donor is someone who chooses to donate give his or her corneas after their death to people who need them. All donated corneas are carefully tested to make sure they are healthy and safe to use. There are different types of corneal transplants. In some cases, only the front and middle layers of the cornea are replaced.
In others, only the inner layer is removed. Sometimes, the entire cornea needs to be replaced. Eye disease and injuries can damage the cornea. Here are some common eye problems that can lead to a damaged cornea:.
Your entire cornea may need to be replaced if both the front and inner corneal layers are damaged. This is called penetrating keratoplasty PK , or full thickness corneal transplant. Your diseased or damaged cornea is removed. Then the clear donor cornea is sewn into place. PK has a longer recovery period than other types of corneal transplants. Getting complete vision back after PK may take up to one year or longer.
With a PK, there is a slightly higher risk than with other types of corneal transplants that the cornea will be rejected. Sometimes the front and middle layers of the cornea are damaged. In this case, only those layers are removed. The endothelial layer, or the thin back layer , is kept in place. This transplant is called deep anterior lamellar keratoplasty DALK or partial thickness corneal transplant.
DALK is commonly used to treat keratoconus or bulging of the cornea. Healing time after DALK is shorter than after a full corneal transplant. There is also less risk of having the new cornea rejected. This causes the cornea to swell, affecting your vision.
Endothelial keratoplasty is a surgery to replace this layer of the cornea with healthy donor tissue. It is known as a partial transplant since only this inner layer of tissue is replaced. The damaged corneal layer is removed through a small incision. Then the new tissue is put in place. Just a few stitches—if any—are needed to close the incision.
Much of the cornea is left untouched. This lowers the risk of having the new cornea cells being rejected after surgery.
Your ophthalmologist will talk with you about corneal transplant surgery. You will discuss why you need this surgery, how it can help you see better, and what you can expect during and after surgery. Once you decide to have a corneal transplant, a date will be chosen for surgery. That date may change if a good donor cornea is not ready for you at that time. Tell your ophthalmologist about all the medicines you take. He or she will tell you if you can keep taking them before surgery.
You may need to stop using blood thinners before surgery.
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